Recently,the research interest in the catalytic conversion of biomass into chemicals and biofuels has been growing.In this study,we have successfully prepared a heterogeneous catalyst (K-10 clay-Mo) by the immobilization of molybdenum acetylacetonate [MoO2(acac)2] on montmorillonite K-10 clay (K-10 clay-Mo).The catalyst showed high catalytic activity in selective oxidation of the aldehyde group of HMF into 5-hydroxymethyl-2-furancarboxylic acid (HMFCA).