An efficient process was developed for the conversion of carbohydrates into 5-hydroxymethylfurfural (HMF). A series of cation-exchanged montmorillonite K-10 clay were prepared as the heterogeneous catalysts for the conversion of carbohydrates into HMF, and chromium-exchanged K-10 clay (K-10 clay-Cr) was found to be the best catalyst for this transformation. A high HMF yield around 95% was obtained from the dehydration of fructose either in dimethyl sulfoxide (DMSO) or in [BMIM]Cl. Results demonstrated [BMIM]Cl was superior to DMSO for the conversion of glucose into HMF, and HMF yield of 51.9% was obtained from the dehydration of glucose at 120 degrees C after 2 h in [BMIM]Cl. Furthermore, the developed methods were also effective for the synthesis of HMF from other carbohydrates. Particularly, a satisfied HMF yield of 48.7% could be obtained from the inedible and abundant cellulose. In addition, the catalyst was effectively recycled six times without significant loss of activity. (C) 2013 Elsevier Ltd. All rights reserved.