Cu-Pd supported on active carbon (AC), in which Cu/Pd ratio is strictly controlled, is an excellent catalyst for selective hydrogenation of NO3- to harmless products in the presence of H-2 at low partial pressure. 3.6 wt % Cu; 2.0 wt % Pd/AC, coupled with another Pd/AC catalyst, showed high selectivity to N-2 (98% at 298 K), while suppressing NH3 production (2% selectivity, 0.5 from 100ppm of NO3-). Modification of the Cu-Pd/AC catalyst with PTFE results in further enhancement; the activity more than tripled, while suppression of NH3 production was retained.