Biochars were used for the removal of Cr6 + ion. The maximum adsorption capacity of adsorbents was pH 1.5 for both adsorbents. The Langmuir isotherm model best fitted the data of the adsorption of Cr6 + ion. Adsorption capacities were 0.474 mmoL/g for OSBC and 0.308 mmoL/g and for CSBC.