: The dilute solution property of segmented poly(ester urethane)s obtained by the reaction of aromatic diisocyanates, 4,4′-methylene diphenylene diisocyanate, and 2,4-tolylene diisocyanate with poly(ethylene glycol)adipate and 4,4′-dihidroxydiethoxydiphenyl sulfone as chain extender, using a multistep polyaddition process, was studied by viscometry in N,N-dimethyl-formamide at 17–45°C. The correlation between hydrodynamic volume, coil density at a given concentration, and unperturbed dimension calculated from viscosity measurement, was discussed as a function of temperature. Also, for the studied samples, we analyzed the contribution of the hard segments composition to these properties.