The heat capacity of poly(oxymethylene), poly(oxyethylene), poly(oxytrimethylene), poly(oxytetramethylene), poly(oxyoctamethylene), poly(oxypropylene), Poly(oxymethyleneoxyethylene), poly(oxymethyleneoxytetramethylene), poly(oxy‐1,4‐phenylene), poly(oxy‐2,6‐dimethyl‐1,4‐phenylene), ploy(oxy‐2,6‐diphenyl‐1,4‐phenylene) and poly[oxy‐2,2‐bis(chloromethyl)trimethylene] is reviewed on the basis of measurements on 35 samples reported in the literature. The crystallinity dependence is critically evaluated and a set of recommended data for each polyoxide is derived. Entropy, enthalpy, and Gibbs energy functions are calculated. The data have been compared to that of polyethylene and the contribution of ‐O‐group has been evaluated. This paper is the third in a series which will ultimately cover all heat capacity measurements on linear macromolecules.