Abstract: A new approximate concentration profile model for batch adsorption in a spherical adsorbent is proposed.The whole process of batch adsorption is divided into two stages.The first stage is that adsorption front moves from the surface of particle to its center.The second stage is a process in which adsorbate is accumulated in the intraparticle.Both concentration profiles of two stages are assumed to be cubic approximation of sphere radius.Compared with exact solution and other approximate models such as parabolic concentration profile and n -th concentration profile,the new model is closely matched with exact solution and is more accurate than n -th and parabolic models,especially during the initial adsorption period when Biot number is greater.This model can be used in the calculations of complex process of unsteady adsorption of spherical adsorbent.