Groundwater pollution with high nitrate concentration has become an important environmental and health issue. Catalytic reduction of nitrates emerged as a promising technique to remove nitrate in water. In the present study, Pt supported on CuZnAl calcined hydrotalcite catalysts with different Cu/Zn ratios (0.5, 1 and 2) were tested in a continuous reactor for the catalytic reduction of nitrates. These materials were characterized by different techniques such as: BET, TPR, XRD, HRTEM, XPS, FTIR. According to the results, the Cu/Zn atomic ratio in the active support has a strong influence in the nitrate conversion and in the nitrogen selectivity, indicating that the interaction of copper in the support plays an important role. The highest nitrogen yield is achieved with a Cu/Zn ratio 1. Also, the incidence of the Pt metal loading was studied in the range of 0.5-2%. This variable does not present a significant influence in the catalytic activity compared to the Cu/Zn ratio, within the range studied. Furthermore, catalysts are stable for this reaction. (C) 2011 Elsevier B.V. All rights reserved.