Dilatometric studies have been performed on the pure poly(ethylene glycol) of average molecular mass 400 g.mol(-1)(PEG-400). From these studies, molar volumes and volume expansion coefficients (alpha) of this sample have been estimated at different temperatures. Using the data, a number of thermodynamic, thermo-acoustic and anharmonic parameters of the sample have been evaluated. All these parameters have been discussed to throw light on the internal structure, molecular order, anharmonicity and intermolecular interactions.