The adsorption kinetics of benzene, toluene and their binary vapor mixtures were measured on Ajar-activated carbon with a differential adsorber bed (DAB) rig and analyzed using the heterogeneous finite kinetics model [D.D. Do, K. Wang, AIChE J., 44 (1998) 68]. The size distribution of the slit-shaped micropore (MPSD) and the Lennard-Jones potential theory are employed to account for the adsorption energetic heterogeneity of the system. This MPSD is compared with the Fore size distribution (PSD) derived from high-pressure methane adsorption data with the Grand Canonical Monte Carlo (GCMC) technique. It is found that, with three mass transfer mechanisms being used to describe the uptake in activated carbon and the Maxwell-Stefan equation being used to describe the bulk phase diffusion, the finite kinetics model can fit the pure component adsorption kinetics of benzene and toluene and has the capability to simulate the multicomponent adsorption kinetics of their mixtures on Ajar-activated carbon.