In the present study, the processes of adsorption of denim blue by Fe-zeolitic tuff from aqueous solutions at different pH values were determined. The parameters, K-d(n), K-d(i), Phi(n), pK(a) were accurately predicted by applying the linear model to sorption isotherms at different pH values of denim blue. Maximum removal of denim blue was observed at pH values between 3 and 5, where neutral species are the main components of the solution. The results indicate that pH has a pronounced effect on denim blue sorption depending on the conditions of the system.