Removal of crystal violet dye (CV) and methylene blue dye (MB) from aqueous solution using activated carbon prepared from Acacia Nilotica sawdust (ACS) has been reported. The physico-chemical properties of ACS such as surface morphology, surface area, pore volume and composition are determined by proximate, BET, SEM and FTIR analyses. Batch experiments are performed to see the effect of different parameters like adsorbent dose, pH, contact time, initial dye concentration and temperature for CV and MB removal. The kinetic studies are carried out using pseudo first and second order kinetic models. To examine the nature of adsorption, to find and optimize the best-fit isotherm, Langmuir, Freundlich, Redlich-Peterson and Radke-Prausnitz isotherm equations along with ARE, MPSD and HYBRID error functions are used. The adsorption of CV and MB dyes onto ACS follows Redlich-Peterson isotherm and second order kinetic model. The maximum removal CV and MB is found to be 99.64% and 99.96% for the concentration of 50 mg/L and 41.71% and 95.14% for the concentration of 500 mg/L, respectively. The optimum adsorbent dosage for CV and MB are found to be 8 g/L and 10 g/L respectively with 1 h contact time at 303 K temperature. The thermodynamic effect of CV and MB onto ACS show the endothermic nature of sorption.