A pressure exchanger for the transfer of pressure energy from a high pressure fluid stream to a lower pressure fluid stream wherein a generally cylindrical housing contains a rotor having a plurality of channels extending axially therethrough and a pair of end covers which slidingly and sealingly interface with respective end faces of the rotor. The end covers are supported against deformation by high pressure upon the end covers in an inward direction, as by exerting a balancing comparable outward axial force upon inward surfaces of the end covers through the employment of pressure-balancing chambers that are in communication with a high pressure fluid region at one end cover.