Indium trichloride (InCl3) was used as catalyst for the conversion of monosaccharides into 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) in aqueous medium. 5-HMF yield of 60% (10min) and LA yield of 57% (60min) were achieved from glucose at 180 degrees C with 2.5 mol% of InCl3, and 5-HMF yield of 79% (15 min) and LA yield of 45% (60min) were obtained from fructose under the same conditions. Moreover, the isomerization process between glucose and fructose was investigated through the comparative studies of glucose/fructose mixture with different ratios as substrates. It was found that InCl3 could not only catalyze the isomerization of glucose to fructose as well as the reverse direction, but also have the positive effects on the dehydration and conversion of monosaccharides. Based on this, a catalytic mechanism of dehydration of glucose and fructose promoted by InCl3 was proposed. (C) 2014 Elsevier B.V. All rights reserved.