Abstract: A process is provided for secondary and tertiary recovery of hydrocarbon from hydrocarbon bearing formations. Apparatus for carrying out the process is also provided. Combustion products are formed in a bipropellant generator, the combustion products being at supercritical pressures and temperatures relative to steam. Water and steam are combined with the combustion gases, which may include steam, and forced through the center of a cooling jacket which is provided to cool the walls of the well bore. Chemical additives may be added to the mixture of combustion gases and steam between the bipropellant generator and well bore or below the cooling jacket.