D-Glucose and cellobiose were converted into 5-hydroxymethylfurfural (HMF) by rare earth metal chlorides LnCl(3) (Ln = Sc, Y, La) in N,N'-dimethylacetamide (DMA). Both conversion and selectivity strongly depend on the ionic radii of the rare earth metal center. Conversion of fructose into HMF proceeds significantly faster and with higher selectivity than of glucose, suggesting a mechanism that involves the transformation of glucose into fructose as a crucial, rate determining step. (C) 2012 Elsevier B.V. All rights reserved.