A new ionic diol, 1,2-dihydroxypropylphosphonic acid (DPPA), was synthesized from epibromohydrin and triethyl phosphite. DPPA was used subsequently as a chain extender diol in the two-step synthesis of polyurethane ionomers. Both DPPA and the polyurethane ionomers were characterized by Fourier-transform infra-red and H-1 and P-31 nuclear magnetic resonance spectroscopy. Thermal analysis by differential scanning calorimetry was performed on the ionomers.