The adsorption behavior of cadmium on husk of lentil an agro-waste was investigated to understand the mechanism of adsorption as well as to explore its potential in removing cadmium from its aqueous solution. The adsorption process of lentil husk (LH) was found to be a function of pH of the solution, optimum being 5.0. The rate of adsorption of cadmium by LH was very fast initially and attained equilibrium within 60 min following pseudo second order rate kinetics. The study established that 1.0 g LH can adsorb 107.31 mg of cadmium and was successful to reduce the concentration of this metal from the effluent of battery industries. Adsorption process followed Langmuir isotherm model with uniform distribution of metal ions on the surface of the biomass as revealed from X-ray elemental mapping. In binary system the biomass displayed a preference in adsorption of lead over cadmium. The results of Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), chemical modification of functional groups and zeta potential measurement established the binding of cadmium to the biomass through electrostatic and complexation reactions. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.