The paper presents investigation results on propane combustion in argon, carbon dioxide, and water vapor under the conditions of O2 deficiency and high reagent density when they are uniformly heated up to 620 K. Based on time dependences of reaction mixture temperature, the self-ignition temperature of propane was determined. It has been established that the oxidation of propane in an Ar and H2O medium proceeds according to the mechanism of chain-thermal explosion. The results of mass spectrometric analysis showed that oxidation in a CO2 medium is characterized by the lowest degree of propane conversion. It was also found that at a low density of water vapor, the oxidation of propane is accompanied by a high yield of H2. The mechanisms of CO2 and H2O molecule participation in the oxidation of propane are discussed in the paper.