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Abstract Adsorption properties of Cr(III) and Cr(VI) on natural (NCS), acid-activated (ACS) and base-activated (BCS) cherry stalks (CS) in Isparta were investigated in aqueous solutions. Batch adsorption studies had been completed with different initial chromium concentrations, pH, temperature, time and biosorbent dosage. Adsorption rapidly approached an equilibrium state between 10 and 60 min. The results displayed that the adsorption system was suitable for pseudo-second-order kinetics. Equilibrium isotherms (Langmuir, Freundlich and Dubinin–Radushkevich) were measured experimentally. The retention characteristics of Cr(III) onto NCS, ACS and BCS and Cr(VI) onto ACS were represented by Langmuir adsorption isotherms, while Cr(VI) ions onto NCS and BCS were compatible with Freundlich adsorption isotherms. The adsorption process was endothermic accompanied by a decrease in entropy and Gibbs energy. An artificial neural network (ANN) model was improved to estimate the efficiency of Cr(III) and Cr(VI) ion’s adsorption. The ANN model can predict the behaviour of the Cr(III) and Cr(VI) ion's adsorption under different circumstances. The results have shown that NCS, ACS and BCS biosorbents open up new possibilities and potential commercial uses in the cherry stalks.