Hydrogen balloon record...unmanned balloon

[draqon]

What is the record set by a balloon filled with hydrogen for high altitude? :bugeye: Only hydrogen balloon and should be unmanned...are there scientific probes now that use hydrogen for the balloon?

I know everyone uses helium...but I specifically need hydrogen to test an engineering concept.

[Facial]

Make sure to equip it with a lot of wire to discharge static electricity. But then again, it will make it heavier.