CO + 3H2 = CH4 + H2O
Works as an equation, but I don't think that is actually the reaction that takes place if you manage to cause a reaction between Carbon Monoxide and Hydrogen Gas. I think the more common result is:
CO + 2H2 = CH3OH (methanol)
Gaseous carbon monoxide reacts with hydrogen gas to form gaseous methane (CH4) and liquid water?