The capability of the use of chitosan for removing vinyl sulfone and chlorotriazine reactive dyes from aqueous solutions was examined, including equilibrium and dynamic studies. Experiments were performed as a function of dye concentration, and the amount and particle size of chitosan. It was shown that the adsorption capacities of chitosan were comparatively high for the three investigated dyes. The equilibrium data could be best fitted by the Redlich–Peterson equation over the entire concentration range (50–500 g m−3). A comparison of the adsorption capacity among such adsorbents as chitin and powdered activated carbon was made. Two rate parameters were finally obtained to describe the adsorption process on a quantitative basis. These parameters could be well correlated to the amount and particle size of dry chitosan. ©1997 SCI