Using Wilson’s GF matrix method as modified by Higgs for an infinite system, we report normal modes and their dispersion for polyoxymethylene using the Urey-Bradley force field. Heat capacity has been evaluated as a function of temperature from dispersion curves via density-of-states. The results obtained agree well with the experimental data reported in the literature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011