The total interaction parameter at infinitely high polymer concentration, chi(t)(infinity), and the effective exchange energy parameter, <(X)over bar (12)>, of poly(dimethyl siloxane) with n-pentane, n-hexane, n-heptane and n-nonane were determined around room temperature using the inverse gas chromatography technique. The values of chi(t)(infinity) are in agreement with corresponding literature values. The exchange enthalpy X(12) and entropy, Q(12), parameters were determined at the same temperature. The X(12) parameters increase with the carbon number of the n-alkanes, while their temperature dependence is almost negligible. The Q(12) parameters are approximately independent of temperature and carbon number of the n-alkanes.