A solution to the intraparticle diffusion model has been developed on the basis of the pore structure of adsorbents. This global model incorporates the mechanism of external film mass transport, intraparticle macropore surface diffusion, and adsorption at the surface in the micropores limited by a first-order reaction kinetic rate constant. To assess the model, it has been applied to the adsorption of acid and basic dyes onto two adsorbents, active carbon and bagasse pith. The two adsorbents were selected because of their differences: active carbon has a large BET surface area and microporous structure, whereas bagasse pith has a small surface area and only a spongelike macropore structure. The branched pore model developed and tested is able to distinguish these physical-structural characteristic differences between the two adsorbents using two very different adsorbates.