The purpose of this work was to evaluate the adsorption potential of Capsicum annumn seeds, in a batch system for the removal of lead(H) ions from aqueous solutions. The experimental results showed that this agricultural by-product was effective in removing lead(H) ions. The FT-IR analysis indicated that the mechanism involved in adsorption of lead(H) ions by seeds of C. annuum was mainly attributed to lead(H) binding of amino and hydroxyl groups. Adsorption equilibrium approached within 40 min. The adsorption data fitted well to the Langmuir isotherm model. The maximum adsorption capacity (q(max)) was 1.87 x 10(-4) mol g(-1). Pseudo-second-order kinetic model was applicable to all the adsorption data over the entire time range. The thermodynamic parameters indicated that the adsorption process is spontaneous since Gibbs free energy values are negative, which are between -26.92 and -30.77 kJ mol at the temperature range of 20-50 degrees C.