Abstract: Method and apparatus for drying compressed air, for example the compressed air from a compressor in the braking system of automotive vehicles. The apparatus comprises a pair of drying chambers having a regeneratable drying medium therein and connections for causing compressed air to flow alternatively through the two chambers. The apparatus provides a system in which the compressed air is directed through one of the chambers into a receiver for storage or use. A portion of the dried air from the outlet of the first chamber is caused to flow through the second chamber to drive out the moisture from the regeneratable drying medium. When the air pressure in the receiver reaches a maximum level, the apparatus interrupts the flow of dried air into the receiver, directs all of the compressed air from the compressor through the second chamber and directs all of the dried air from the outlet of the second chamber through the first chamber to regenerate the same.