Abstract: In a refrigeration system wherein compressed refrigerant flows from a compressor discharge chamber successively through an oil separator and a condenser to a high pressure receiver, a minor portion of the condensed refrigerant that enters the high pressure receiver is passed through a pump by which its pressure is raised to above that of compressed refrigerant at said discharge chamber. From the pump the refrigerant is passed through an oil cooler in indirect heat exchange with compressor lubricating oil and is then released into the discharge chamber where it desuperheats the compressed refrigerant, thereby also cooling the compressor itself and increasing the effectiveness of the oil separator. The rate of flow of such refrigerant through the oil cooler is controlled to maintain a desired temperature of refrigerant flowing from the discharge chamber to the oil separator.