Introduction: DIY Hydrogen Generator

This Instructable shows, how to build an easy DIY hydrogen generator.

Materials needed for this project:
- Empty container with lid
- Cables
- Pencil
- Luster terminals
- Hot glue gun
- DC Power Supply
- Drill
- Funnel
- Balloon

Step 1: Build the Anode

For the anode, you need an old pencil, a knife, a luster terminal, cables and a hot glue gun.

Take the pencil and strip it with a knife, until you have the lead. Put the lead into the luster terminal and tighten the screw. (Don't screw the terminal too tight, as that will break the lead)

Strip the ends of a cable and put the ends into the other side of the luster terminal.

Seal the terminal and cable with hot glue. Make sure everything is watertight. The only part which mustn't be covered in hot glue, is the lead.

As you can see I used two pieces of lead and put them into two terminals. I connected the two terminals to the same cable. This increases the lead surface, and gives us a higher production quantity.

Step 2: Build the Cathode

For the cathode, you need a cable and a cable stripper.

Strip 10-20cm of the cable and roll it around a pencil. This piece of copper, is the finished cathode.

You can also attach a piece of copper metal to the cathode to increase the surface.

Step 3: Build the Cap of the Container

For this step, you will need the lid of your container, the funnel, a drill, your anode, your cathode and the hot glue gun.

Drill a hole into the lid of your container, the hole should be big enough, for the end of the funnel.
After you drilled the hole, insert the end of the funnel and attach it with hot glue. (Be careful, that the hot glue isn't too hot! If it is too hot it will melt through the funnel and your container.)

After the glue is cold, glue the cathode on the inside of the funnel and the anode on the outside.

Know that you attached the electrodes, drill a small hole into the lid and put the cables through. Seal everything with hot glue.

Step 4: Hack the Power Supply

Before hacking the power supply, please make sure it isn't plugged in!

Hacking a power supply is easy. You only have to connect the green cable with a black cable (ground). Make sure not to solder the two, because in case of a short circuit you have to disconnect the two cables and reconnect them in order to reset the fuse in the power supply (It's a good idea to put in a switch).

The power supply will start running, as soon as the green cable is connected to the ground. Now you have a DC power supply!

To use the power supply, strip a blue cable (-12V) and a yellow cable (+12V). Put the stripped cables into a luster terminal.

Step 5: The Final Setup

Now that everything is finished, you only need to fill the container with tap water (you should also add a bit of salt) and place the lid on top.

Attach the cables to the power supply and turn the power supply on. (You should see small bubbles rising from the electrodes now)

The last step is to put a balloon on top of the funnel, to catch the hydrogen gas.


NEVER attach the hydrogen generator to a normal power outlet.
!ONLY use low voltage currents!

Hydrogen is highly FLAMMABLE make sure you don't burn the gas uncontrolled or in closed buildings. Also make sure, to keep a safe distance when burning the gas.

Step 7: Educational Part

If you are not only interested in building a hydrogen generator, but also in the chemical background, please read this part of the instructable.

Electrolysis is an endothermic reaction. This means, the reaction is only running if you add energy to the system. This is achieved with our DC-Power supply. The power supply pulls the electrons out of the anode and pushes them to the cathode.

The electrons are from the water molecules. The power supply forces the water molecules (HHO) to split into a positive loaded hydrogen Ion (H+) and a negative loaded hydroxide ion (OH-).

Due to electromagnetic forces the positiv loaded hydrogen ions are pulled towards the cathode, and the hydroxide ions are pulled towards the anode.

As the cathode offers electrons to the hydrogen ions, the hydrogen ions become hydrogen gas (HH).

Because the anode pulls electrons, it takes the electrons of the hydroxide ions and the hydroxide ions become hydrogen ions, as well as oxygen gas (OO). The hydrogen ions travel to the cathode afterwards.

Why do we use pencil lead as the anode?:
We use pencil lead as anodes, because metals (except for platinum) are oxidised due to electrochemical reactions in the container. That means if you use an iron anode it would basically rust away while you produce hydrogen. The same thing happens when you use copper. The copper turns into copper oxide. This slows down your hydrogen production and gives the water a bad colour.


oo0oOo0oo (author)2016-04-16

This looks really nice but is the pressure enough to inflate a balloon?

StevenD6 (author)oo0oOo0oo2016-05-07

if you build it properly than yes it is if u want the baloon to float then you need to have a seperate funnel. have the negative side ( hydrogen) bubble through another container with distilled water so the pressure can build up but be careful of static diacharge hydrogen is explosive.

BrandonW55 (author)2016-02-07

Thank you for sharing this. I have looked all over the net and all I keep finding is HHO generators. On a side note, any idea how long the electrods will last in hours? Or how long the gas will keep for, in say a 20 oz plastic bottel? (May consider takeing down all the nonrelavant info.)

Antbal0 (author)BrandonW552016-04-29

this is an hho

bjrmeno (author)2015-12-18

I have a question. Where does the oxygen go? From what I understand, the anode produces one gas and the cathode produces the other. Most electrolysis systems I have seen, have a vent over both and the O2 comes out one and H2 the other.

Am I confused, or would this unit not produce a balloon full of both gases?

Please let me know if you have an explanation. I really want to make a low pressure H2 generator and this seems simple enough to suit my needs.

Also, mythbusters mentioned that tap water and regulat table salt could produce chlorine gas which is also bad news and heavy.


awabo (author)bjrmeno2016-04-08

the anode produces oxygen gas and the cathode produces hydrogen gas and in this case they all end up in the balloon so you have a hydrogen-oxygen mixture in the balloon.

Also if you use salt it will produces chlorine gas but you can replace the it with baking soda and the chlorine will be gone!!

awabo (author)awabo2016-04-08

one thing if you're using salt or baking soda there will be sodium hydroxide which then can be neutralized by adding vinagar to it

rasel88 (author)2016-03-30

Well done good job i also make high power cell which run my motorbike

Goober 2 (author)2015-10-24

Most HHO units call for stainless steel in some manner or fashion. could the stainless steel be replaced for a similar effect?

PysselPappan (author)Goober 22016-01-30

Don't use stainess steel! The Chromium in the steel will produce very toxic chromates that are illegal to put in household drains, or in the ground. AND they are toxic. Very. Don't do it.

bergpa (author)2015-12-06

would a 12 volt battery work as the dc power supply?

Make it BIG (author)bergpa2015-12-18

Yes it would.

tkddms225 (author)2015-08-23

I've been researching hydrogen generators lately, and many people have advised others not to use salt (because it can produce chlorine gas, which is, as you may already know, a very toxic chemical that you would not want to produce). Other than that, great project!

fathant (author)2015-07-28

Any one can help with the lead? :c

AirbourneNation made it! (author)2015-05-09

Thanks, mate, for an easy instructable!

voblak (author)2015-04-12

Try 1000VA toroid where you wind secondary (centre taped) so you have about 5V/200A or even better is 10V/100A. Than use few power diodes in paralel. And you can produce some serious amounts of hydrogen. Also it helps if you put a few drops of HCl into water, so it has lower resistance.

gfetters (author)voblak2015-05-04

How fast will this produce hydrogen. I need about 100cf of hydrogen to for a balloon launch. I would like to produce it at the launch site if possible. If it takes more than an hour to produce this will probably not be viable for my problem.

Make it BIG (author)gfetters2015-05-05

It will DEFINITELY take longer than an hour to produce that amount.

I also think I have to break your dream of being able to produce that amount in that time as a DIY project. (And even transportable)

I did some research and all professional generators which produce such an amount of gas in an hour are as big as a cupboard.

Just as an example.

ashuki (author)2015-04-15

Warning should be in front of any tutorial in my opinion

honey181 (author)2015-04-13

Haha. Yeah! ;)

honey181 (author)2015-04-12

The best, easiest and simplest way to collect hydrogen from water. Nice! :)

Georgeh3 (author)honey1812015-04-13

And oxygen :)

theoriginalrage (author)2015-04-12

How are you generating enough pressure to blow the balloon up?

Georgeh3 (author)theoriginalrage2015-04-12

Sealed container and expansion.

theoriginalrage (author)Georgeh32015-04-12

I finally found it, had to dig through the comments for a while though.

Georgeh3 made it! (author)2015-04-12

I made mine with a Gatorade bottle. I noticed you get more hydrogen with a higher amperage supply. I plan on taking a peice of PVC and another bottle to keep the hydrogen seperated from the oxygen that is generated

flagoworld (author)2015-04-10

If you are going to try to explain the science, you should use scientifically correct terms. Pencil "lead" is actually pencil "graphite" and neither contains nor has anything to do with lead. Lead is toxic and should not be handled without proper protection.

Even solder is lead free these days.

That said, pencils have never been lead. Check out the wikipedia entry on the evolution of pencils. It mentions why people stsrted calling them "lead".

tj.dimacali (author)flagoworld2015-04-12

Pedantic person is pedantic.

Everyone knows that pencil lead isn't really made of lead, and even if they DIDN'T know that, there's absolutely no danger of picking up a pencil with actual lead in it.

Also, if you don't know the difference between pencil lead and actual lead, you really shouldn't be doing this Instructible at all.

Georgeh3 (author)flagoworld2015-04-12

Haha, I agree mostly, except with solder being lead free. Plumbing solder, yes. But any circuit solder that is lead-free is junk.

emartin19 (author)flagoworld2015-04-12

It doesn't matter why the word came to mean what it means. It still means what it means.



a : a thin stick of marking substance (as graphite) in or for a pencil


By the way, let me remind you that 'scientifically correct' does not bode well together with wikipedia.

One can find dozens of false or biased information in wikipedia

Make it BIG (author)flagoworld2015-04-10

I'm sorry but it's not my fault, that whoever called that thing called it pencil lead. I can't write pencil graphite in an Instructable just because it's correct. The thing is still called pencil lead.

I can't reinvent the language just because it's scientifically correct. If I write pencil graphite it's just wrong language, and makes the Instructable harder to understand.

flagoworld (author)Make it BIG2015-04-10

I'm not here to argue, but your point is moot.

That said, consider changing it to say something along the lines of:

"You will need a graphite rod, which can be found in the core of pencils. Though commonly referred to as 'pencil lead', the material used to create pencils is actually graphite."

You will cater to a bigger audience who also recognizes graphite as a stand alone material and to those that have access to graphite on its own without milking the poor defenseless pencils for all they're worth.

jproffer (author)2015-04-12

it should be noted, that this will not produce pure hydrogen. impurities in the water will produce other gasses on the cathode. Do not rely on this method as a source of pure hydrogen.

pshiveshwar (author)2015-04-09

In the end the liquid becomes a stinky residue. It mainly forms at the anode.

How can I prevent it???????????


Make it BIG (author)pshiveshwar2015-04-09

Maybe the anode isn't watertight? Or you are using too much salt, which results in chloride forming at the anode. If the chloride combines with organic impurities it begins to smell (like in a pool).

pshiveshwar (author)Make it BIG2015-04-12

Which salt did u use?????????

Make it BIG (author)pshiveshwar2015-04-12


Make it BIG (author)Make it BIG2015-04-12

I had the same problem, but it only happened after my anode became leaky, and formed ironoxide.

Everything impossible (author)2015-04-11

How fast should this thing produce hydrogen, it seems lik it doesn't work


Depends on the power supply you use. If you have some salt in the water, and at least 24V DC you should see small bubbles rising from the electrodes. This happens as soon as you switch on the power.

NotI1 (author)2015-04-07

I have a few technical questions regarding your set up.

I'm concerned that the insulation around the cables may crack or split. (because they're submerged... indefinitely...)

In the event that this happens, I see a potential for a spark gap, which is very apparently dangerous.`.

Can you comment on this?

How are your terminals holding up?

Lastly, If you had another 20$ to spend on this, what improvements would you make to it?


Make it BIG (author)NotI12015-04-07

Hi Notl1,

I don't really understand your concern, why should the isolation of the cable break? It is made of flexible plastic and won't break just because it is in contact with water. There is also not the possibility, that there is pressure building up between the copper and the plastic part of the cable, as bubbles of gas would escape at the open end of the cable before being able to make the plastic "explode".

If you use normal cables (not old and broken ones) I see no reason why the isolation should break.

I'm sorry but I'm not a native english speaker so I don't understand what you mean with "How are your terminals holding up?". The terminals are normal screw terminals from the hardware store. They are attached to the funnel with hot glue.

If you want to spend 20$, you should see if you can buy a platinum electrode from somewhere (although I think they cost more than 20$ as 1g of platinum is ~35$) as the graphite can break after some time under water.
You should also get a piece of copper metal as an electrode (some kind of thin sheet metal) as it has a bigger surface. And a bigger graphite electrode (or the platinum one).
Last but not least get a DC power supply with more than 24V DC but less than 80V DC. (I would recommend not going above 50-60V as everything else gets dangerous)

But you could also change much more (for example the container). I didn't do this, as I wanted to create a simple DIY project, from material laying around.

With best regards,

NotI1 (author)Make it BIG2015-04-07

Exposure to water causes the insulation around cables to become brittle and crack. Especially salt water. It's a big problem houses that are flooded.

the cable in the container will eventually be exposed to the water because the plastic insulation will eventually split and crack from the water. some people here want to add salt to the mixture. this will make the insulation crack and split faster. It is probably important to note that you will need to inspect the wires each time they are reused in case of damage.

I asked "how are your terminals holding up" I meant: "are the terminals still in good shape? the glue isn't peeling? the metal around the terminal ins't rusting?"


Make it BIG (author)NotI12015-04-07

Ok now I understand your concerns. In general (as you already figured out) it takes time, even for saltwater, to damage a cable. And even if the Cable was damaged, the damage would be under water causing a "spark" under water, so that nothing can ignite. After the spark the fuse of the power supply/house would prevent further sparks.

The terminals are in a pretty good shape, the only problem so far is, that my graphene is quite porous, and therefore already quite broken. But there is still no water leaking into the luster terminals. Just make sure the terminals are covered in hot glue. The glue is no problem at all.

I hope I was able to answer your questions, best regards,

NotI1 (author)Make it BIG2015-04-10


Thanks Very much!

Brooksdiy (author)2015-04-08

Ok my mistake on the mpg obtained after adding in my self made "hydrogen on demand" generator which really put's out Brown's gas, the mix of both gasses from H2O. I reported that after installing my "on demand" Brown's gas generator I obtained 52.4 mpg which is incorrect. After checking my notes I find that I in fact obtained 39.4 mpg which is indeed a 50% increase of mpg over the 26.2 mpg I was getting before adding the device. I stand corrected

Light_Lab (author)2015-04-08

Hey Make it BIG don't worry about all the controversy you have stirred up. You have done a pretty good job. All feedback is good if it is accurate and constructive. I just put up a new Instructable around 11 hours ago and already I have had to deal with 3 issues that I didn't cover well enough for the nit pickers. Don't be scared off I hope to see more from you.

nevyn.hira (author)2015-04-07

Given that you're splitting water into it's hydrogen and oxygen particles, aren't you collecting *both* oxygen and hydrogen?

snatr (author)nevyn.hira2015-04-08

My thoughts as well. Unless they only have the cathode under the funnel. But it doesn't look like it from the pics. The other problem I see is the resistance of the balloon to filling.

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Bio: I am a german student and joined Instructables, because I like to build your projects and share mine with you.
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