Chars were produced from an Illinois No. 2 bituminous coal under various pyrolysis and activation conditions and tested for their molecular sieve properties. The amount of N2 compared to the amount of CO2 adsorbed by each char was used as a preliminary indicator of its molecular sieve properties. This relatively simple, but apparently useful test was confirmed by successfully characterizing the well-known molecular sieve properties of a commercial zeolite and molecular sieve carbon. In addition, coal chars having relatively high surface areas (800-1800 m2/g) were produced and tested for their molecular sieving capabilities. These carbon materials, which have high adsorption capacities and relatively narrow pore size distributions, should be ideal candidates for the commercial production of CMS.