In this study we report on a vacuum swing adsorption process and adsorbent which allows simultaneous production of high purity methane and high purity carbon dioxide from a biogas feedstock. This is a departure from conventional biogas purification processes which focus on production of high purity methane while venting the lower purity methane/carbon dioxide stream. Using NaUSY as the adsorbent, and based on experimental and simulation data, we are able to produce product purities of 98% CH4 and 95% CO2 in the two product streams, respectively, for an energy consumption of 0.23 GJ/tCO(2) from a feed containing 50/50% CH4/CO2.