A series of water-borne polyurethanes were prepared by prepolymerization process. Isophorone diisocyanate, polyester diol, and dimethylol propionic acid were used to conduct the reaction. H-1- and C-13-NMR spectra of the raw materials and products thereof were measured with a high-resolution spectrometer, and their chemical shifts were assigned. H-1- and C-13-NMR spectra of urethane group and urea group were compared. The chemical shifts of side products from the reaction between water and the isocyanate group were also analyzed. Much useful information may be obtained from the NMR analysis of this kind of polyurethanes. (C) 2003 Wiley Periodicals, Inc.