The present invention is directed particularly to an improved method usingowder metallurgy for the manufacture of the grooved cooling wall of a liquid-propellant rocket combustion chamber. The surface of an inner cylinder constituting the cooling wall is formed with cooling grooves, and these grooves are densely filled up with a filler such as paraffin wax. Thereafter, metal powder which will provide an outer cylinder is compression-molded to a predetermined thickness around the inner cylinder. This metal powder is the same material as the material of the inner cylinder. After the paraffin wax which is the filler is evaporated and removed, the compression-molded metal powder body is sintered in a furnace. During this sintering heat treatment, the inner and outer cylinders are rigidly joined together by the sintering reaction between the atoms of the inner cylinder and the atoms of the metal powder.