<p>The performance of on-board SCR catalysts has been in high demand due to the increasingly stringent vehicle emission requirements. Diesel engines typically have exhaust gas temperatures below 250&#xa0;°C at cold start and idling; the catalyst carrier’s actual temperature field is uneven, with high-temperature areas ranging from 430 to 530&#xa0;°C; and high-temperature exhaust gas is also produced during DPF regeneration. Therefore, this work aims to develop composite metal oxide catalysts with a wide active temperature window. Mn-doped vanadium-based SCR catalysts were successfully synthesized via the solution combustion method, and their physicochemical properties and catalytic performance were systematically investigated. Their chemical structure, performance, and physical characteristics were then examined and described. It was discovered that adding Mn significantly increased the catalyst’s low-temperature activity but slightly compromises its high-temperature performance. Between 190&#xa0;°C and 440&#xa0;°C, the TiV_0.1Mn_0.1O_<i>x</i> catalyst with <i>r</i> = 0.1 performed the best, with NO_<i>x</i> conversion and N₂ selectivity both exceeding 80%. Mn doping had no discernible impact on the specific surface area, pore volume, or pore diameter, according to BET characterization. The XRD patterns only showed anatase TiO₂ diffraction peaks, suggesting that the active ingredients were widely distributed across the carrier surface. The total acid quantities on the four catalysts’ surfaces were comparable, according to NH₃-TPD curves, and the distribution of acid amounts moved to lower temperatures as the Mn content increased. Some catalysts experienced sintering problems, according to TEM pictures, but their surfaces featured rich pore architectures.</p> Graphical Abstract <p>Schematic diagram of V-Mn SCR catalyst structure and performance regulation</p>