The potential use of copper slag (CS) as an adsorbent for removing arsenic contaminant from water was examined. The influence of solution pH, initial arsenate (As(V)) and arsenite (As(III)) concentrations, and adsorbent dosage was investigated by batch experiments to elucidate the adsorption mechanism of arsenate onto CS. The adsorption kinetics indicated that the second-order kinetic model best described the adsorption process. The adsorption data was analysed by the isotherm models, and was well fitted by the Langmuir model. The maximum removal of As(V) and As(III) achieved was 98.76% and 88.09%, respectively at an adsorbent dose of 10 g/L with an initial As(V) and As(III) concentration of 300 mu g/L This study showed that copper slag is a suitable adsorbent for removal of arsenic from water, with a capacity to reduce arsenic levels to < 10 mu g/L, below the limit set for water by World Health Organization.