DESCRIPTORS: Rocket motors *Hydrogen, *Air, *Combustion, *Ignition, Gases, Shock waves, Fuel injection, Fuel injectors, Supersonic flow, Schlieren photography, Mixtures, Combustion cham ers, Combustion chamber gas s. A study of the shock-induced combustion of hydrogen-air mixtures was made in a small Mach number 3 wind tunnel at a total pressure level of 45 psia. Combustion was induced by a normal shock wave which resulted from the interaction of two oblique shock wave produced by wedges on the tunnel walls. Significantly different phenomena were observed when the fuel injector was moved from the subsonic portion of the n zzle into the throat. With fuel injection in the throat, ignition denoted by emission glow from the sodium introduced with the hydrogen did not occur until some distance downstream of the normal shock wave. Some data are presented showing this delay as a function of the static temperature behind the shock wave.