As a part of abating formaldehyde emissions of urea-formaldehyde (UF) resin adhesives, using dynamic mechanical analysis (DMA), we attempted to investigate the influence of the formaldehyde to urea (F/U) molar ratio on the thermomechanical curing of UF resin adhesives with different F/U molar ratios. The thermomechanical curing of these UF resin adhesives was characterized with DMA parameters such as the gel temperature, maximum storage modulus, peak temperatures of the storage and loss moduli, and maximum tan delta. As the F/U molar ratio decreased, the gel temperature of UF resin adhesives increased, whereas the maximum storage modulus, an indicator of the rigidity of UF resin adhesives, decreased. The maximum tan delta increased with the F/U molar ratio decreasing, and this indicated that the UF resin adhesive with a low F/U molar ratio had greater damping than the one with a high F/U molar ratio. A decrease in the rigidity of the UF resin with a lower F/U molar ratio was explained by the calculated crosslinking density, which decreased with the F/U molar ratio decreasing. These results partially explained why UF resin adhesives with lower F/U molar ratios showed relatively poor adhesion performance when they were applied to the manufacture of wood panels. (C) 2008 Wiley Periodicals, Inc.