Propoxylation of lactitol [4-O-beta-D-galactopyranosyl-D-glucitol] under alkaline conditions afforded poly(ether polyol)s (PEP) which have been characterized by their unsaturation content, alpha color, hydroxyl number, viscosity, hygroscopicity, and molecular weight distribution. The analogous sucrose-based PEP were prepared for comparison. Lactitol was found to require shorter reaction times and produced lighter-colored polyols than did sucrose. Polyols produced from lactitol displayed similar physical properties to sucrose-based PEP. Molecular weight analysis by GPC using the universal calibration method showed lactitol PEP to have polydispersities between 1.04 and 1.07. Negligible decomposition of lactitol during propoxylation was confirmed by C-13-NMR and GPC. H-1-NMR of trifluoroacetyl derivatives of lactitol PEP afforded secondary determination of M(n). In addition, rigid polyurethane foams (PURF) formulated with lactitol-, sucrose-, or commercial sucrose-glycerin-based polyols and PAPI 27 were prepared and characterized. Lactitol-based PURF were found to compare favorably with sucrose-based foams, displaying a density and compressive strength of 28.9 kg/m(3) and 1.213 X 10(5) N/M(2), respectively.