A hydrogen hybrid cycle system configured to convert heat into mechanical work by burning a H2 and an O2. The hydrogen hybrid cycle system comprises a H2 source, an O2 source, a combustion chamber, a first steam injected gas turbine, a load, a heat recovery steam generator and a water pump. The H2 source provides the H2 to the combustion chamber. The O2 source provides the O2 to the combustion chamber. The combustion chamber burns portions of the H2 and the O2. The hydrogen hybrid cycle system burns the H2 and the O2 at or near stoichiometry in the combustion chamber. The hydrogen hybrid cycle system cools the combustion chamber with at least one of a cooling steam and a water.