Isotherms for 2,2-dimethylpropane, 2,2,3-trimethylbutane, and ammonia adsorbed on a microporous silica gel all exhibit a steep segment in the desorption branch of the hysteresis loop. The extent of hysteresis decreases with increasing temperature and we utilize this phenomenon to derive the pore size distribution of the adsorbent. The pore size distribution is independent of adsorbate and, within a limited range of pore radii, is in reasonable agreement with the results of a method developed by K.S.W. Sing and co-workers.