Kinetic and thermodynamic studies of Am (Ill) sorption on Na-bentonite have been investigated under the given conditions. Comparisons of linear and non-linear methods of three kinetic rate equations and four thermodynamic isotherms have been tested on the experimental data. The results show that sorption of Am (III) on Na-bentonite can be represented by a pseudo-second-order rate equation, and the non-linear pseudo-second-order kinetic expression could fit the kinetics better. The thermodynamic parameters (Delta H-0, Delta S-0 and Delta G(0)) of Am (III) sorption on Na-bentonite indicate that the sorption process was spontaneous. Freundlich isotherm model is the best-fit model to the experimental data for the sorption of Am (III) on Na-bentonite. Furthermore, the non-linear method is a better way to describe the sorption isotherm than the linear method. Non-linear methods are found to be the better way to obtain the kinetic and thermodynamic parameters.