Cadmium detection was investigated by Square Wave Anodic Stripping Voltammetry (SWASV) measurements by using boron doped diamond electrodes with different morphologies from micro to nanocrocrystalline grains as Boron Doped Diamond (BDD) and Boron Doped Nanocrystalline Diamond (BDND), respectively. The argon concentrations, in the argon/hydrogen ratio, used were 0, 50, 60, 70, and 80 vol.%. SWASV technique was applied in 4 x 10(-4) mol L-1 ammonium acetate buffer pH 42. The peak currents were measured for Cd2+ concentration ranging from 1 to 20 mu g L-1. This change in film grain size and roughness affected how cadmium was deposited on the electrode surfaces, thus affecting its electroanalytical response from SWASV measurements as well as its selectivity. For all electrodes cadmium detection limits (DL) were lower than 1 mu g L-1 while for BDND electrode DL reached 0.016 mu g L-1. These values are lower than that required by the Brazilian Health Ministry for potable water (1 mu g L-1) and confirm that diamond electrodes are a suitable mercury-free method to determine cadmium trace levels in water. A strong correlation between the electrode selectivity and its grain size also confirmed the best performance of BDND electrode. (C) 2017 Elsevier B.V. All rights reserved.