A highly efficient iron-catalyzed production of 5-hydroxymethylfurfural (HMF) from sugar is reported. The dehydration of fructose and sucrose has been studied in the presence of different iron salts and co-catalysts. As a result, it was found that fructose and sucrose could be efficiently and selectively converted to HMF using a combination of environmentally friendly FeCl3 and tetraethyl ammonium bromide (Et4NBr) as the catalytic system. For instance, 86% HMF yield at full conversion of fructose was obtained for 2 h at 90 degrees C in air. The effects of catalyst concentration, reaction time and reaction temperature were investigated in detail. The electronic absorption spectra of different catalysts were recorded, and the FeCl3Br- ion was considered as the active catalyst species. (C) 2011 Elsevier B.V. All rights reserved.