Thus, external-film transfer coefficients were found to be in the range of 3 × 10−6 to 35 × 10−6 m s−1, 1 × 10−6 to 8 × 10−6 m s−1 and 1 × 10−6 to 11 × 10−6 m s−1 for guava, teak and gulmohar leaf powders, respectively, in the chosen temperature range. At the same time internal diffusion coefficients were in the range of 0.1 × 10−12 to 1.9 × 10−12 m2 s−1, 0.1 × 10−12 to 0.6 × 10−12 m2 s−1 and 0.2 × 10−12 to 1.3 × 10−12 m2 s−1 for guava, teak and gulmohar leaf powders, respectively. It was evident that film-pore diffusion model could satisfactorily describe kinetics of methylene blue adsorption onto the three low-cost adsorbents used.