A low-formaldehyde-emission methylol urea/triethanolamine composite was synthesized through in situ esterification of formaldehyde with triethanolamine and subsequent copolymerization of the synthesized polyester with methylol urea. The effects of the addition of triethanolamine to the polymerization process on some physical properties of the synthesized copolymer were evaluated. The copolymer was characterized with IR spectroscopy and macrophase-separation techniques. At a given triethanolamine concentration, the composite exhibited macrophase-separation behavior between that of pure methylol urea and pure polyester. IR spectra showed the presence of the polyester moiety in the composite. The values of the moisture uptake, formaldehyde emission, melting point, and elongation at break of the copolymer were within acceptable levels required in the coating industry. Therefore, the methylol urea/polyester copolymer resin could have potential as a binder in the coating industry. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116: 645-653, 2010