Abstract: MnOx-Fe2O3 mixed oxides prepared by coprecipitation method were investigated for the complete oxidation of formaldehyde. The catalyst showed 100% formaldehyde conversion at a temperature as low as 80 ℃. The effect of reaction temperature, space velocity, inlet formaldehyde and O2 content on the catalytic behavior of the MnOx-Fe2O3 mixed oxides were further examined. The life test of the catalyst for 500 hours showed that the catalytic activity of the MnOx-Fe2O3 was unstable. The FTIR analyses suggested that carbonatation was the main reason for catalyst deactivation.