Abstract: High side pressure in a transcritical vapor compression cycle system is regulated by varying a liquid inventory of a low pressure refrigerant receiver provided in a circuit of the system. The circuit includes a compressor, a gas cooler, a throttling valve, an evaporator and the receiver connected in series in a closed circuit operating at supercritical pressure in a high pressure side of the circuit. The degree of opening of the throttling valve is controlled to regulate the high side pressure in the circuit. It is possible to control capacity, and it also is possible to achieve minimum energy consumption for a given capacity requirement by regulating high side pressure.