It has been shown that most of the previously reported empirical rate equations for kinetics of adsorption at the solid/solution interface show high relative errors at the initial times of adsorption. In the present work we made a modification onto pseudo-first-order and pseudo-second-order models and presented a new empirical rate equation, called the modified pseudo-n-order (MPnO) model. The results of fitting to the experimental data show that the MPnO model has low relative errors in the whole range of adsorption time. (C) 2010 Elsevier B.V. All rights reserved.