DeNO_x activity of 0.5% Pd–30% La_0.5Ba_0.5CoO₃/Al₂O₃ formulation is analysed in single-NSR and combined NSR–SCR systems, using response surface methodology (RSM). Operational maps are built for any combination of reaction temperature in the NSR and SCR beds and H₂ concentration. A 4% Cu/SAPO-34 is used as the SCR catalyst. Results for single-NSR allows tuning operational conditions in coupled NSR-SCR technology to maximize NO_x-to-N₂ conversion, with minimum NH₃ and N₂O productions. Control of H₂ concentration and temperature in the NSR system allows generating the stoichiometric amount of NH₃ to eliminate NOx slipping. The tuned coupled NSR–SCR system achieves high N₂ yield under wide operational range (T=175–425 °C; C_H2=2–4%). Specifically, N₂ yield reaches 92% when NSR and SCR catalysts work at 300 °C and 3% H₂ is injected, with NH₃ slip and N₂O production nearly zero. This provides a promising alternative for NO_x removal in diesel aftertreatment systems.