The catalytic reduction of nitrates with hydrogen in aqueous phase was studied in a trickle bed reactor using different activated carbon-supported metallic catalysts. Continuous experiments were performed at ambient conditions (25 degrees C and 1 atm) at different space-time values in the range of 25.8-103.3 kg(cat) h/mol. The activity of monometallic catalysts based on Pd, Rh, Cu, and Ni was low in all the cases, yielding nitrate conversions below 15%. The introduction of a second metal produced a synergistic effect, improving the catalytic activity and the selectivity toward N-2. That increase in activity was more pronounced when using Pd or Rh combined with Cu, reaching nitrate conversions above 80% in the case of Pd Cu catalysts. The catalyst with a Pd/Cu mass ratio of 2:1 (Pd050Cu025) also showed the lowest selectivity to nitrite and the highest to N-2. Metal leaching was always below detection limits for Pd and Rh, whereas in the case of Cu and Ni, significant metal concentrations were found in the reaction effluent, the leaching of Ni being higher. The initial pH significantly affected both activity and selectivity of the bimetallic catalysts, the maximum activity being achieved within the 6-7 range, which also led to the lowest Cu leaching. The use of a two-step reaction system was checked using two different catalysts, a bimetallic Pd Cu in the first and a monometallic Pd catalyst in the second. With this two-step system, an important reduction of the nitrite originating in the first stage was observed, and the formation of N-2 at the expense of ammonium was favored.