As part of the Special Research Go-operative Sonderforschungsbereich 255 "Transatmospheric Flight Systems" the thermofluid dynamics of supersonic reacting flows were experimentally studied. Fuel (gaseous hydrogen, liquid kerosene) was injected into a vitiated Mach 2.15 air stream. The supersonic flame was stabilized by means of fuel self-ignition. The interaction between gas dynamics and chemical kinetics was investigated employing optical measurement techniques (schlieren technique, Rayleigh technique, OH self-fluorescence). Special attention has been focussed on the influence of shock waves on the self-ignition mechanisms. The use of liquid hydrocarbons as fuel in a supersonic combustor was the second research topic. Fundamental differences were found to exist in the ignition characteristics of gaseous hydrogen and liquid hydrocarbons. The analysis of the test data led to the formulation of a gas dynamic feedback mechanism, which helps to explain the operating characteristics of kerosene-fuelled combustors.