Fuel cell systems comprising ammonia borane or derivatives thereof as fuel and an anode and/or cathode which comprises a non-noble metal (e.g., copper) or a non-metallic substance (e.g., an iron electron-transfer mediating complex) as a catalyst are disclosed. Fuel cell systems comprising ammonia borane or derivatives thereof as fuel and a peroxide as an oxidant are also disclosed. Uses of the fuel devices are further disclosed.