Abstract: Carboxylated multi-wall carbon nano-tubes (MWCNT′s) was dispersed in Nafion solution, and dropped on the surface of glassy carbon electrode (GCE) to prepare MWCNT′s-Nafion modified GCE (MWCNT′s-Nafion/GCE). In the determination of Cd2+-ion, the test solution in a NaOAc-HOAc buffer solution of pH 4.8 was pre-reduced and enriched for 350 s at -1.1 V, Cd2+-ion was then stripped from the electrode by scanning in the range from -1.2 V to -0.4 V and determined by differential pulse anodic stripping voltammetry. Oxidation peak potential of Cd2+-ion was observed at -0.84 V, at where linear relationship between values of peak current of Cd2+-ion and its concentration was obtained in the range of 5-100 μg·L-1, with detection limit (3S/N) of 2.54 μg·L-1. The proposed method has been used in the determination of cadmium in water sample, giving results obtained in consistency with those obtained by ICP-MS.