Pressure swing adsorption (PSA) processes are used for the production of high purity hydrogen from steam methane reforming off-gas (SMROG) and refinery off-gases (ROG). A variety of commercial PSA processes for the production of Ha with or without a by-product (CO2 from SMROG), as well as PSA processes for direct production of ammonia synthesis gas (from SMROG), are reviewed. The equilibrium ad(de)sorption characteristics of the components of SMROG and ROG feed gas on an activated carbon, a zeolite, and a silica gel are reported, and the criteria for adsorbent selection in these PSA processes are discussed. Recent ideas to increase the H-2 recovery from these PSA processes by integrating them with selective surface flow membranes or other PSA units an reviewed.