<p>The catalytic removal of trace formaldehyde (HCHO) at ambient temperatures is crucial for improving indoor air quality, necessitating the use of monolithic catalysts over traditional powder forms for real-world applications. In this study, an aluminosilicate fiber-woven ceramic filter paper (CFP) was selected as the substrate, onto which a Mn₂O₃ catalyst was in situ coated via a combustion method utilizing Mn(NO₃)₂ as the oxidant and glycine as the fuel. The resulting monolithic Mn₂O₃/CFP catalyst was compared to a MnO₂/CFP catalyst, prepared by direct decomposition of Mn(NO₃)₂ on the same substrate. The Mn₂O₃/CFP catalyst exhibited superior characteristics for HCHO oxidation, including a more porous architecture, higher redox capability, and an abundance of surface-active oxygen species with enhanced mobility of surface lattice oxygen. These features enabled the Mn₂O₃/CFP catalyst to achieve significantly higher HCHO conversion at room temperature (90%) compared to the MnO₂/CFP catalyst (21%). Additionally, in a durability test carried out in a mode of dynamic flow at room temperature, the Mn₂O₃/CFP catalyst maintained a high HCHO conversion rate of 66% over 11 days, demonstrating its potential for practical indoor air purification applications.</p> Graphical abstract <p></p>