The biosorption of chromium ions from aqueous solution by Citrus reticulata was studied in a batch adsorption system as a function of pH, contact time, chromium ion concentration, and biosorbent dosage and biosorbent size. The biosorption capacities and rates of chromium ions onto Citrus reticulata were evaluated. The Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. It was determined that the best fitted adsorption isotherm models were obtained. The kinetic experimental data were properly correlated with the second-order kinetic model.