Hydrogenation of nitrate (NO3 (-)) in water was studied with 0.8 x10(-3)-3.2 x10(-3) mol/dm(3) of reactant in the temperature range of 293-313 K over palladium promoted Ag catalysts. Pd-Ag catalysts with a low ratio of Ag/Pd were characterized by high efficiency in the reduction of nitrates. The degradation of nitrates followed approximately first order decay and the estimated apparent activation energy was about 4 kJ/mol.