nope, its combustible, and highly so.
BMW is doing pretty well with hydrogen combustion engines.
check it out...
http://www.worldcarfans.com/news.cfm?newsid=2040920.001&bmw=1.html/country/gcf
I have an engineer friend who is working on hydrogen injection into gasoline and diesel burning engines. From what he tells me by injecting a small amount of hydrogen in the intake cycle the efficiency goes way, way up. He claims the cost to convert any gasoline or diesel engine will be less than $1000.