For the first time, experimental studies of detonation combustion of hydrogen in a demonstrator of a air-breathing ramjet engine with Mach number from 4 to 8 have been performed. The studies were performed in the "Transit-M" wind tunnel of ITAM RAS. As a result, continuous and pulse-longitudinal detonation modes of hydrogen combustion in the annular combustion chamber were registered andfor the first time. The thrust characteristics of the demonstrator were measured. The positive effective thrust has been registered.