Biosorption of Congo red dye from an aqueous solution was investigated by the Groundnut shell in batch studies at different sorbent dosage (0.2 to 0.6 g per 100 mL), pH (1 to 6) and initial dye concentration (20 to 120 g/L). Langmuir and Freundlich adsorption isotherm models were used to represent the equilibrium data. The Freundlich isotherm model was found to be fitted very well with the experimental data when compared to Langmuir isotherm model. The results showed that the equilibrium uptake capacity was found to be increased with decrease in biomass dosage. The equilibrium uptake capacity was influenced by the initial dye concentration. The sorption results were analysed for pseudo first order and pseudo second order kinetic model. From the result, it was observed that the kinetic data fitted very well with the pseudo second order rate equation when compared to the pseudo first order rate equation.