<p>Selective catalytic reduction is widely applied to various industries for NO_x removal. In this study, CeVO₄-based catalysts were modified with iron and cobalt to enhance catalytic activity. Each transition metal was partially substituted into either the Ce or V site at 0.2 molar ratio. The synthesized catalysts exhibited both partial incorporation of the transition metal into the CeVO₄ lattice and the formation of secondary metal oxide phases. In particular, the V site substitution led to lattice expansion, CeO₂ formation, and smaller particle sizes, while the Ce site substitution caused lattice contraction and larger particle sizes. All of the catalysts were coated on the alumina pellets to protect the reactor from increasing pressure during the catalytic reduction reaction and boost the catalytic activities, that were evaluated under both oxygen absence and 1 mol% oxygen flow conditions. Among them, CeVO₄-CeO₂-Co₃V₂O₈/Al₂O₃ catalyst (Ce:V:Co = 1:0.8:0.2 molar ratio) exhibited the highest NO conversion. This result was attributed to synergistic effects, including the promotional effect of CeO₂, and enhanced oxygen migration via the asymmetric Co³⁺-O-V⁵⁺ phase. Therefore, the transition metal incorporation, particularly Co substitution at V sites, effectively enhances the catalytic activity of CeVO₄-based catalysts in the NH₃-SCR process.</p>