Abstract: A device for low temperature refrigerative drying of compressed air and other gases includes a gas/gas heat exchanger in one passage of which a gas to be dried is pre-refrigerated by heat exchange with gas which has already been refrigeratively dried. The pre-refrigerated gas is then passed through a trap to remove liquid therefrom and then selectively supplied to a gas passage in one of a pair, or more, of evaporators wherein the gas is refrigeratively dried at low temperature by heat exchange with a refrigerant, after which the refrigeratively dried gas is circulated through the other passage of the gas/gas heat exchanger and then discharged for use. Each evaporator is provided with a refrigerant circuit selectively supplied from a refrigerant gas condenser unit with high pressure refrigerant via an expansion valve for refrigerative drying or with warm refrigerant via an unfreezing valve for melting frozen condensate in the evaporator.