In this work, determination of cadmium(II) using square wave voltammetry (SWV) was described. The method is based on accumulation of these metal ions on kaolin platinum electrode (K/Pt). The K/Pt performance was optimized with respect to the surface modification and operating conditions. The optimized conditions were obtained in pH of 5.0 and accumulation time of 25 min. Under the optimal conditions, the relationship between the peak current versus concentration was linear over the range of 9 x 10(-8) to 8.3 x 10(-6) mol L-1. The detection limit (DL, 3 sigma) was 5.4 x 10(-9) mol L-1. The analytical methodology was successfully applied to monitor the Cd(II) content in natural water. Interferences were also evaluated. (C) 2009 Elsevier B.V. All rights reserved.