The feasibility of using adsorbent-coated microchannels for a pressure swing adsorption (PSA) process for carbon dioxide removal is investigated by analyzing the effectiveness of depressurization. As a result of large adsorbent particle size and the correspondingly large mass transfer resistances and a diffusion-based process design, the cycle times for conventional adsorbent-bed-based PSA processes are long, and gas removal capacities normalized with adsorbent mass are modest. However, this computational investigation of the depressurization stage that involves the pressure, temperature, and adsorbent capacity response in a microchannel analogous to bed depressurization for Zeolite SA and 13X and activated carbon shows that gas removal capacities during depressurization are greater than those for a conventional bed-based PSA process under the same operating pressure limits, feed compositions, and stage times. An activated carbon monolith yields the highest operating gas removal capacity during depressurization when compared to other adsorbents as a result of the smaller selectivity of the activated carbon. A parametric study on the microchannel geometry shows that an increase in channel size aids in fast depressurization because of the reduced frictional resistance at the microchannel walls. It is found that the use of adsorbent microchannels in adsorption purification techniques can yield benefits through the reduction of total cycle time and overall plant capacity.