Biosorption has attracted attention as a cost-effective tool for the treatment of metal-bearing wastewater. While using novel biosorbents, optimization of operating conditions becomes more important for the efficiency of the process. In this study, a novel biosorbent i.e. Alstonia scholaris leaves were used for biosorption of Cr (VI) from aqueous media. The effect of various parameters, such as contact time of solution with biosorbent, temperature, pH, biosorbent dose and agitation speed were studied. A comparative study of modification of biosorbent using acid and base was also performed. It has been found that acid treated Alstonia scholaris leaves have greater biosorption capacity as compared to untreated and base treated leaves. Optimum conditions for removing Cr (VI) using acid treated biosorbent were: 0.2 g/50 mL of biosorbent, 50 oC temperature, 15 minutes contact time, 300 rpm stirring speed and 2.0 pH. Langmuir and Freundlich isotherms were also employed to evaluate maximum biosorption capacity of untreated and chemically treated Alstonia scholaris leaves for Cr (VI).