The kinetics and the mechanism of Dowex 50WX8 catalyzed conversion of d-fructose to 5, 5′-[oxybis(methylene)]bis[2-furaldehyde] via the intermediate 5-hydroxymethylfurfural was studied in DMSO. The first order rate constants for two step process was determined at 383 and 393 K by monitoring the concentrations of 5-hydroxymethylfurfural and 5, 5′-[oxybis(methylene)]bis[2-furaldehyde]. The activation energies for d-fructose to 5-hydroxymethylfurfural conversion and dimerization to 5, 5′-[oxybis(methylene)]bis[2-furaldehyde] were determined as 48.2 and 24.5 kJ mol−1. A detailed mechanism with four acid catalyzed dehydration steps is proposed for the one-pot conversion of d-fructose to 5, 5′-[oxybis(methylene)]bis[2-furaldehyde] based on 1H NMR studies in DMSO-d6 at 393 K.