The orthogonal array design has been used to determine the optimum conditions for the cementation of cadmium from a synthetic zinc sulfate solution and hence to achieve the highest cementation efficiency and the best robustness of the quantitation from the least number of trials in a laboratory scale. Cementation was performed using zinc powder. The orthogonal array L-9 (3(4)) that comprises four parameters at three levels was chosen. The parameters and their levels were as: zinc powder quantity (Z): 1, 1.2 and 1.5 times of stoichiometric quantity of cadmium; time (t): 4, 8 and 12 min; temperature (T): 25, 35 and 45 degrees C and zinc powder particle size distribution (R): nos. 1-3. The ultimate optimum cementation conditions were found to be Z(1) (equal to stoichiometric quantity of cadmium), T-1 (25 degrees C, R-3 (no. 3) and t(1), (4 min). Under these conditions, cementation percentages for cadmium and nickel were 95.83% and 6.63%, respectively. (c) 2006 Elsevier B.V. All rights reserved.