Introduction: Generating Hydrogen... Without Batteries

Picture of Generating Hydrogen... Without Batteries

Generate hydrogen quickly and easily without those costly 6V batteries! Using H20 Electrolysis, generate hydrogen (and chlorine gas) with only water! The setup will take only 5 to 10 minutes, and can be safely left running overnight. Generate bottles of hydrogen with ease!

This Instructable is not only my first... it is also for the Science Fair contest.


Step 1: The Parts

Picture of The Parts
You only need four things:

  • A wall transformer ($4.77), which is available here on 12 Volt Transformer]

  • Salt... optional

You can complete this project for as little as $4.77 or as much as $29.87.

Step 2: What to Do

Picture of What to Do

First, put the water in a bowl and mix in salt (optional). The salt will simply increase the speed of the reaction.
Next, cut the plug off of the wall transformer. Next, install a fuse to prevent the transformer from breaking in the event of a short. A good fuse is available here on In addition, you can screw on a switch like this. Separate and strip the two wires (you can get a wire stripper here: ). Plug the transformer in and submerge both leads in water. To enhance production, you can use pencil graphite by sharpening both ends of a pencil.
One should be rapidly generating bubbles, which are full of hydrogen. Once you know this works, go ahead and tape the lead that does not generate bubbles to the side of the container (still under water). Next, take a test tube or bottle filled with water and while keeping the bottle/tube filled, submerge the open end under water. This prevents air from entering. Thread the wire that generates bubbles into the tube.

Step 3: Other Capturing Ideas

Picture of Other Capturing Ideas

Now that you can capture hydrogen, you can also try to capture chlorine gas bubbles (basically oxygen). Simply place a separate bottle over the other lead. This gas is generated much more slowly.

If you like explosions, you have two options:
Remove the bottle of hydrogen and stick a match inside. BOOM!
Use one bottle to capture both gases. This creates the perfect mixture for an explosion. Be careful!

Please not that using salt produces chlorine. Because chlorine is heavier than air, it will fall to the ground. Chlorine is a very dangerous chemical that can suffocate you. To prevent a catastrophe, use another bottle/test tube to capture it.
Another alternate is to use baking soda instead of salt. This will produce oxygen instead of chlorine.

Step 4: Holding the Bottles

Picture of Holding the Bottles

Always hold the bottles opening-down (as if you were pouring out water). Remember, hydrogen is much lighter than air... it floats up. It does not fall down.

I hope you enjoyed this Instructable. While the concept is not new, using a wall transformer is a unique and inexpensive solution. This is a fun experiment... but as with all explosions, be careful!

Step 5: Explanation

Picture of Explanation

WARNING: Science Content:
When current from the wall transformer passes through the water, the water molecules are split into hydrogen and hydroxide ions. The lead with bubbles, which produces Hydrogen, can be explained through the following equation:*
2H2O(l) + 2e− → H2(g) + 2OH−(aq)
The other lead, which produces nothing unless a better electrode, like graphite or platinum is used, can produce hydroxide. The formation of hydroxide ions then turn into oxygen (or chlorine if salt water is used). The following equation* defines the reaction:
2H2O(l) → O2(g) + 4H+(aq) + 4e−
The overall reaction is defined in the following equation:
2H2O(l) → 2H2(g) + O2(g)

NOTE: equations are from here.


mister1130 (author)2016-09-16

does this create less power than is needed to generate it. Like other hydrogen generators

buckminsterfullerene (author)2009-09-19

You said that it was a single "molecule of hydrogen," but all elements are atoms, unless bonded. A molecule is a covalently bonded group of atoms.

a hydrogen atom only has one hydrogen molecule... goofy

TrentH7 (author)robinettebobby2016-08-29

Actually most hydrogen found in nature is exists as H2 like O2, N2, I2, F2, Cl2 and Br2. Or as I learned the 'diatomic' molecules:

HonI FiCl Brs (pronounced 'honey fickle burrs') - Thanks Coach Pauley...26 years later I still remember!

fred.fanackerpan.3 (author)2016-08-28

So how much hydrogen is in the average bucket of water?

perlpower (author)2007-08-29

O and chlorine is NOT the same as oxygen, it is toxic and does not help explosions, DO NOT BREATHE IN CHLORINE!!!!! it WILL fill your lungs and starve you of oxygen. The good thing about it is that it is heavier than air so this is hard to do.

VIRON (author)perlpower2007-08-29

Mixed Hydrogen and Chlorine will spontaneously explode without ignition. Breatheing chlorine or hydrogen chloride will surely cause a life threatening trouble breatheing and instant loss of consciousness. Carelessness almost absolutely guarantees that this will happen. How about using baking soda instead of salt? Using copper wire is OK, it may turn the saltwater green by making copper chloride. The positive wire just dissolves slowly. You can protect the transformer from shorting wires with a 1 amp fuse, or a cheaper small 10 ohm resistor (brown black black). If you do short it, then the fuse or resistor burns up instead.

icinnamon (author)VIRON2007-08-29

When you say spontaneously explode, do you mean it can happen at any moment? I thought you needed a match...

VIRON (author)icinnamon2007-08-29

H and O needs a match. H and CL just goes boom whenever it feels like it.

icinnamon (author)VIRON2007-08-29

Hmmm.... I just tried setting off both with a flame and nothing happened...

triggernum5 (author)icinnamon2008-04-10

Hydrogen and Chlorine don't spontaneously react, they need a near UV photon to initiate under otherwise presumably safe conditions at STP.. Its pretty dang close to spontaneous though in practise, in all cases, you should separate the gasses whatever they be if you're dealing with much more than test-tube fulls.. BTW, the chemistry outlined isn't exactly correct.. Its a redox reaction, not an acid base thing..

merseyless (author)triggernum52008-04-25

if it needs near uv wouldn't sunlight or most other household lights do this

firesirt (author)merseyless2012-06-20


icinnamon (author)VIRON2007-08-29

As with all projects of this nature, it can be dangerous. Common sense can be the best protective action... My water turned green, but that doesn't really matter

dagenius (author)perlpower2009-08-30

Nobody said that it was the same as oxygen.

bloke2022 (author)dagenius2009-09-18

the author did.

dagenius (author)bloke20222009-09-26

Oh? When?

bloke2022 (author)dagenius2009-09-27

he said "chlorine, (which is basically oxygen)" or something like that

bloke2022 (author)bloke20222009-09-27

sorry, he said "you can also try to capture chlorine gas bubbles (basically oxygen)"

emuman4evr (author)perlpower2008-04-25

In the event of this happening shouldnt you stand on your head and exhale alot so the chlorine sinks back down your throat? Just a theory...

rickharris (author)2007-08-29

Err Chlorine isnt basically O2 - It is toxic, an irritant and not a good thing - In the 1st war they used it as an anti personnel gas. Thats why most web instructions for doing electrolysis specifically exclude salt. try to fing something better or you may gas everyone at the fair.

icinnamon (author)rickharris2007-08-29

lol. I mostly used salt to improve conductivity. Also, I am not capturing the chlorine... just the hydrogen.

rickharris (author)icinnamon2007-08-29

I realise why you use the salt BUT not capturing the chlorine means you allow it to escape - It's not good in the air around you or your fellow students. Have a try to find a more suitable alternative and write up why in your science fair project for more credit.

BuildIt6000 (author)rickharris2011-06-18

The chlorine is produced in such a low quantity that it isn't dangerous

icinnamon (author)rickharris2007-08-29


jconrad66 (author)2010-02-19

Why not just mix a solution of HCl with sodium in a flask, Your byproducts would be NaCl (aq){salt water} and free H2 Gas.  If you wear an apron thick rubber gloves and face shield it is a relatively safe process. 

Jaycub (author)jconrad662010-10-18

Sodium is expensive, but you could use aluminum instead. The main problem is you don't get the oxygen with the hydrogen.

spider87 (author)2010-09-28

So, anyone had this problem:

I was using a 12v 1a DC charger. The wire was producing bubbles but not fast enough for me so i stripped some copper wire and made coils out of it to give it more surface area and then soldered the coils to the current cables. I built a 3 tier system top of bucket->bottom of bottle1; mid of bottle 1->bottom of bottle 2. Filled the bucket 3/4 of the way up with water, bottle1 was half way (just below the mid hose) with water and bottle2 was 1/8th full of water (just enough to require pressure for the oxygen to come out)... I did this so bottle1 would fill with hydrogen while the heavier air got pushed out of bottle1 by the pressure and into bottle2 to be released.

Well, I came back an an hour later and the water had turned blue and foamy... Anyone have any thoughts on why? (We have softened water so maybe that's part of it?)

Jaycub (author)spider872010-10-18

It's the copper. You can't use copper electrodes, go for stainless steel if you can or if you are super rich you could buy platinum plated electrodes. The cathode (negative wire) can be a cheaper material like mild steel or stainless steel. Also you should use sodium hydroxide (lye, sold as drain cleaner under the Rooto brand) or potassium hydroxide.That way only hydrogen and oxygen are produced.

batman96 (author)2010-01-07

 use stainless steel electrodes 

weasel5i2 (author)2009-04-27

Try using gold plated electrodes, I've found that they still corrode but they seem to last longer than anything else I've tried. Also, if you add salt to the water, you won't get any oxygen. The chloride ions will replace the oxygen ions at the anode, and you'll end up releasing chlorine gas instead! ALso, I discovered that the released chlorine is even MORE corrosive to the electrodes. I ended up with bluish-green copper chloride caked on the electrodes when the salt water leaked in and ate the wiring. They say sodium bicarbonate is better to use.

Eucherplayer (author)weasel5i22009-11-14

A few months (well several) late, but I have found that using the graphite rods from 6 Volt "Heavy Duty" batteries wrapped at the base with 14 gauge (house) wiring (with the insulation left on except for the ends) works best.  I then used a mini muffin pan and potted both electrodes (at their bases) with household wax.  This has allowed only the graphite to be exposed to the acid solution - no visible corrosion at this point on either electrode.

dagenius (author)weasel5i22009-08-30

It is also fact that platinum works best. That is why many people will use platinum wire to make a double helix electrolizer.

Berkin (author)2009-01-12

You don't absolutely have to use a 12-volt transformer. You can use anything higher then that.

pyroelfears (author)Berkin2009-02-02

you can use any sort of transformer , the higher the voltage and amperage, the faster hydrogen in made. But be careful, high amperage is fatal

Berkin (author)pyroelfears2009-02-03

I am pretty educated on the dangers of high voltage and current. Thanks though!

dagenius (author)Berkin2009-08-30

I think he means that the hydrogen will ignite.

Berkin (author)dagenius2009-09-04

No, he's referring to electrocution.

budsiskos (author)Berkin2009-02-03

i use a 9 volt transformer for my setup and it works great. very quick

Berkin (author)budsiskos2009-02-03


Dr_Stupid (author)2008-07-16

fix this section, pictures are too blurry for any reliable reproduction.

dagenius (author)Dr_Stupid2009-08-30

Well maybe he would have replied to you by now if you had given him advise on how to fix whatever section you are talking about, and how he could make the pictures sharper.

Mercurio (author)2007-11-24

I have a question. How many amps do you need for electrolysis to happen? How many volts? P.S. : what I mean is what's the least amount of amps and volts needed.

sempri_fi (author)Mercurio2007-12-13

1-3 volts is idea, and as many amps as the water will pull is best, having upwards of 50 or so will work for even the best setups.

Mercurio (author)sempri_fi2007-12-15

Thank you, but I still want to know the amount of amps. I'd appreciate a thorough response. Again thank you.

dagenius (author)Mercurio2009-08-30

He said "as many amps as the water will pull." This means that water will only take a certain amount of current from the transformer, rather taking as much as the transformer gives.

dagenius (author)dagenius2009-08-30

I know, 2 years late, but I couldn't resist.

bylerfamily (author)sempri_fi2009-01-05

Would 4 volts work?

bylerfamily (author)Mercurio2009-01-09

Well I just tried 4 volts and it works great.It is 550 amps.

bylerfamily (author)bylerfamily2009-06-02

milliamps :-)

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