Abstract: A filling apparatus for filling receiving vessels with compressed gas lowers the temperature of the compressed gas in response to the filling pressure of the receiving vessel. As an internal pressure within the receiving vessel approaches a value indicative of a filled vessel, the temperature of the compressed gas is reduced to counter the effect of heat caused by increasing pressure within the vessel. The temperature of the compressed gas is reduced by slowing the compressor and allowing the gas to dwell for a longer period within a heat exchanger between stages of compression. In addition, the temperature of the compressed gas is reduced by increasing the efficacy of the heat exchanger such as by increasing the rate of air flow over the heat exchanger. Accordingly, engine speed, fan speed and compressor speed each can be varied according to various arrangements of the filling apparatus to reduce the temperature of the compressed gases being introduced into a receiving vessel.