A novel process for gas separation, called pressure swing permeation, was investigated to elevate the relatively low permeate pressure by pressurization with high-pressure feed gas, thereby reducing or eliminating additional permeate compression costs where a pressurized permeate is required. This process uses two or more membrane modules and operates in a cyclic;fashion, with each module repeatedly undergoing the sequential steps of feed admission and permeation, residual removal, permeate reception, permeate pressurization, and product withdrawal. The unsteady-state permeation associated with pressure swing permeation was studied parametrically, and a bench-scale unit compromising two hollow-fiber membrane modules in parallel was tested for H-2/N-2 separation to demonstrate the effectiveness of the process. The permeate product at a pressure as high as the feed pressure can be produced without using a compressor. This is impossible with traditional steady-state processes where a pressure differential across the membrane must be maintained. The pressure swing permeation is analogous to pressure swing adsorption and has the potential to be synergistically integrated with the pressure swing adsorption process for enhanced separation of gases.