Some History channel instead will actually answer this question for you. Not only do we already know that Oxygen and the metal particles in the skin material were the combustion materials, but the Nazi’s actually figured it out back then. They buried the truth to avoid not appearing as the technological supreme power on the planet. Hydrogen is of course flammable, but it’s not a combustible by itself. the Hydrogen fueled the intense fire, but photos and studies of the crash show that it was not started with Hydrogen being present at all. Beyond the Nazi part, the really interesting thing is that some of these conclusions were realized by burning an actual piece of the Hindenburg’s outter skin.