The use of adsorption for the characterization of the micropores within zeolites was studied. An experimental procedure for the determination of adsorption isotherms in zeolites is demonstrated. A modified static technique was successfully employed for the acquisition of equilibrium adsorption data. Adsorption isotherms were measured over a variety of zeolites. Nitrogen at 77 K and argon at 77 and 87 K were compared as adsorbates. The use of argon at 77 K is recommended, while nitrogen at 77 K can also be used and has advantages for adsorption in the smallest pores (i.e., < 5 Angstrom) if the pressure is measured very accurately, We did not see any particular advantages of using argon at 87 K, as was suggested by prior investigators. Current commercial equipment does not accurately measure high-resolution isotherms in a reasonable time.