To decrease the formaldehyde emission of urea-formaldehyde (UF) bonded products at source, monomethylol urea (MMU) was chosen to react with glyoxal (G), a nonvolatile and nontoxic aldehyde, to prepare a novel glyoxal-urea-formaldehyde (GUF) cocondensed resin. The GUF resins were synthesized with different MMU/G molar ratios, and the basic properties were tested. The GUF resins were characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, carbon-13 nuclear magnetic resonance spectroscopy and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The results show that the synthesized GUF resins remain stable for at least 10 days at ambient temperature. Conjugated structures, and large amounts of OH, NH, CN, and CO groups with different levels of substitution exist in the GUF resin. There are two repeating motives in the MALDI-TOF-MS spectrum of the GUF resin, one of 175 ±1 Da and a second one of 161 ± 1 Da. Moreover, the peaks due to the dehydration condensation reaction of MMU also appear in the spectra. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41009.