The mass transfer coefficients for adsorption of a multicomponent n-octane"thiophene"benzene mixture in a fixed NaX zeolite bed are calculated using a mathematical model. The zeolite particle size is found to have the decisive effect on mass transfer in the mixture adsorption process. Reduced particle size increases the phase-contact surface, drastically curtails adsorbent particle use-up time, i.e., time of absorption of a substance from its surface, and raises the mass-transfer coefficient fourfold.