The hydrogen combustion characteristics have been studied in a late-injection (near TDC) hot surface ignition engine. As a supplemental experiment, the mode of combustion was observed in a constant volume combustion chamber by the schlieren method. Consequently the combustion process, that was the flame propagation initiated by a hot surface through heterogeneous hydrogen jets, was not the same as that of a diesel engine. The experimental results in test engine showed the optimum number of injection holes and the effect of intake air swirl for better mixture formation.It was observed that the combustion was frequently accompanied by non-negligible combustion pressure vibrations at all engine operating conditions. The experimental results suggested that, besides the vibrations in the air column between pressure sensor and combustion chamber, the cylinder gas vibrated at a characteristic frequency corresponding to the cylinder size, and this was caused by the high combustion velocity of hydrogen and a long ignition delay until a flame propagated to the adjacent jet.