A dual reflux (DR) PSA cycle that combines the features of a conventional (stripping reflux) PSA cycle with those of a new enriching reflux PSA cycle is analyzed to show its potential for separating gas mixtures. On the basis of isothermal equilibrium theory applied to linear isotherms, the ultimate separation is carried out where the binary feed is separated into two pure components with 100% recovery of each component. This very idealized analysis reveals that such a separation is possible over a wide range of conditions, even with pressure ratios as low as 1.1. This analysis also reveals that low throughputs and high heavy component recycle ratios are inherently associated with DR PSA cycles, both of which may be detrimental to the process economics. High throughputs and low heavy product recycle ratios are indeed achievable, but only when using low pressure ratios and less selective adsorbents, both counterintuitive results that make sense when considering the perfect separation is always being achieved. Although these trends may not carry over to actual practice, because the model developed here is overly simplified and invalid under certain conditions, this analysis shows that it may indeed be entirely feasible to separate a binary gas mixture into two relatively pure components with very high recoveries using a DR PSA cycle operating with a very low pressure ratio and, hence, expenditure of energy. (C) 2004 American Institute of Chemical Engineers.