A recently reported layered zirconosilicate Na2ZrSi4O11 displays good activity in the isomerization of glucose to fructose in water at mild conditions. Part of the activity derives from the homogeneous base-catalyzed reaction due to exchange of the sodium ions of the layered zirconosilicate in water. Following ion-exchange, the isomerization is mainly catalyzed by the basic sites of the re-used heterogeneous zirconosilicate catalyst. Combined with the solid acid Amberlyst-15, 5-hydroxymethylfurfural (5-HMF) can be produced from glucose in a one-pot reaction. In a THF/H2O mixture solvent system, 5-HMF was obtained with 45 % selectivity at 87 % glucose conversion at a temperature of 180 A degrees C in 1.5 h.