The use of different chemically modified cassava waste biomass for the enhancement of the adsorption of three metal ions Cd, Cu and Zn from aqueous solution is reported in this paper. Treating with different concentrations of thioglycollic acid modified the cassava waste biomass.The sorption rates of the three metals were 0.2303 min(-1) (Cd2+), 0.0051 min(-1) (Cu2+), 0.0040 min(-1) (Zn2+) and 0.109 min(-1) (Cd2+), 0.0069 min(-1) (Cu2+), 0.0367 min(-1) (Zn2+) for 0.5 and 1.00 M chemically modified levels, respectively. The adsorption rates were quite rapid and within 20-30 min of mixing, about 60-80% of these ions were removed from the solutions by the biomass and that chemically modifying the binding groups in the biomass enhanced its adsorption capacity towards the three metals. The results further showed that increased concentration of modifying reagent led to increased incorporation, or availability of more binding groups, in the biomass matrix, resulting in improved adsorptivity of the cassava waste biomass. The binding capacity study showed that the cassava waste, which is a serious environmental nuisance, due to foul odour released during decomposition, has the ability to adsorb trace metals from solutions. (C) 2003 Elsevier Ltd. All rights reserved.