Abstract: An off-axis rotary valve especially suitable for high-temperature vacuum tight fluid switching. A valve cylinder with an off-center opening(s) therein is mounted between two end seals. The end seals engage the circumferential edges of the valve cylinder and perform the functions of axially locating the valve cylinder, sealing the end faces of the cylinder, and providing for communication between the valve cylinder and fluid inlets and outlets. Means are provided for spring-loading the seal faces with the corresponding valve cylinder faces, and means are provided for rotating the valve cylinder.