The phase behaviour of blends of high-molecular weight poly(N-vinyl pyrrolidone) (PVP) with short-chain poly(ethylene glycol) (PEG) of M-w = 400, prepared by drying their solutions in a common solvent (ethyl alcohol), was studied using DSC. Upon heating of cool-quenched samples a single glass transition was observed, followed by an exotherm corresponding to cold crystallization of excess PEG, a melting endotherm, and an endotherm corresponding to vaporization of absorbed water. The temperatures of glass transition (T-g), PEG cold crystallization (T-c), and melting (T-m), along with the change in heat capacity (Delta C-p) between the polymer＇s glassy and rubbery states at T-g, vary with blend composition and hydration. As a result the T-g/T-m, T-c/T-m and T-c/T-g ratios for PVP-PEG blends are functions of composition. PVP-PEG compatibility is due to H-bonding of PEG terminal hydroxyls to the carbonyls in the PVP repeating units. Large negative deviations of T-g values from the calculated weight averages, found mainly for PVP-overloaded blends, signify strong PVP-PEG interaction and free volume formation. (C) 2000 Elsevier Science Ltd. All rights reserved.