The objective of this research was to enhance adsorption capacity of Acacia nilotica (keekar) sawdust for the abatement of chromium bearing wastewater and to investigate the effect of process parameters on adsorption capacity. The sawdust was activated by acid wash and functionalized subsequently with formaldehyde. Functionalization of activated sawdust raised its chromium removal efficiency of almost 10% as compared to its adsorption removal efficiency of HCl treated sawdust in a batch adsorption study. Adsorption kinetic data provided better fitting with pseudo second order model. Maximum adsorption capacity calculated through the best fitting Langmuir model was 6.34 mg.g(-1) and 8.2 mg.g(-1) for HCl treated and formaldehyde functionalized sawdust adsorbents, respectively. The adsorption of Cr(VI) was endothermic when studied by varying temperature from 20 degrees C to 50 degrees C for both activated and functionalized adsorbents. (c) 2017 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.