Abstract: Integral coupling of reaction with a single-bed rapid cycle pressure swing adsorber provides a hybrid device having improved performance characteristics including better separation and more efficient reactions. A single packed bed containing a mixture of catalyst and adsorbent is featured. Gaseous reactants are fed into the bed in a sequence including inflow, relax, and backflow, portions. The hybrid device, designated as a periodic separating reactor (PSR), enhances both the total conversion and selectivity of reactions. In an illustrative example with respect to CO oxidation, conversion 2.5 times that typically exhibited for the corresponding steady-state plug flow reactors was observed. The separation performance (selectivity) of the hybrid device/process can be enhanced, illustratively for irreversible reaction systems, up to 10.sup.4 times that possible in pressure swing adsorption processes without reaction.