Hydroxycarbonate precipitation of nickel in a pellet reactor was investigated in a previous study (Guillard, D.; Lewis, A. E. Ind. Eng. Chem. Res. 2001, 40 (23), 5564-5569)(1) in order to gain an understanding of the precipitation processes occurring inside the reactor. This paper presents the results of an attempt to establish conditions for optimum nickel removal and to map the response surface representing the response of the total nickel concentration to changes in a number of operating parameters. It was established that, of the five parameters investigated (carbonate/nickel ratio, pH, nickel feed concentration, number of feed points, and recirculation ratio), the first three had the most significant influence on the efficiency of nickel removal in the reactor for the range of conditions investigated. At optimum conditions, 98% removal of nickel was achieved, with the concentration of total nickel in the effluent being reduced from 69.5 to 1.38 ppm. Significant variability in the results prevented a global optimum from being found, and only a stationary point could be established.