The adsorption of mercury ions from aqueous solutions on rice husk has been investigated as a function of appropriate electrolyte, contact time, concentrations of adsorbent and adsorbate, and temperature. The radiotracer technique was used to determine the distribution of mercury. Maximum adsorption was observed at 0.01 mol.dm(-3) acid solutions (HNO3, HCl, H2SO4, and HClO4) using 1.0 g of adsorbent for 1.30 X 10(-3) mol.dm(-3) mercury concentration in 5 minutes of equilibration time. Studies show that the adsorption decreases with an increase in the concentrations of all the acids. The adsorption data follow the Freundlich isotherm over the range of 1.3 X 10(-4) to 2.6 x 10(-3) mol.dm(-3) mercury concentration. The characteristic Freundlich constants. i.e., 1/n = 0.89 +/- 0.05 and A = 208 +/- 2.1 m.mol.g(-1), have been computed for the sorption system. The uptake of mercury increases with a rise in temperature. Thermodynamic parameters, i.e., Delta G degrees, Delta S degrees, and Delta H degrees, have also been calculated for the system. The sorption process was found to be endothermic. Application of the method to the effluents of medium-sized industries showed that 9.9 kg of rice husk was sufficient for their decontamination.