Metal-organic frameworks (MOF) are nanoporous materials with potential applications in adsorption separations, catalysis, and gas storage. Atomistic grand canonical Monte Carlo simulations were used to study the selective adsorption of CO2 over other gases, e.g., N2, CH4, and H2 in several classes of MOF to explore the possibilities for the removal of CO2 from flue gas. Comparisons of predicted single-component isotherms and heats of adsorption were made with published data. Predictions for mixtures were used to make suggestions for possible separations applications. This is an abstract of a paper presented at the 2007 AIChE Annual Meeting (Salt Lake City, UT 11/4-9/2007).