Novel polyurethanes (PUs) based on 1,3-bis(hydroxymethyl) benzimidazolin-2-one and 1,3-bis(hydroxymethyl) benzimidazolin-2-thione as hard segments with two aromatic diisocyanates, viz., 4,4'-diphenylmethane diisocyanate and toluene 2,4-diisocyanate, were prepared. Polymer structures were established by Fourier transform infrared and nuclear magnetic resonance spectroscopy. Morphology of the PUs was studied by differential scanning calorimetry and thermogravimetry. All PUs contain domains of crystalline and amorphous structures as indicated by X-ray diffraction experiments. Furthermore, polymers were insoluble in the majority of organic solvents and, hence, their solution characterization was not possible. (c) 2005 Wiley Periodicals, Inc.