Excess enthalpies, excess volumes, and total vapor pressures were measured for cyclopentanol + pdioxane mixtures at 25 "C. The method of Barker was used to calculate vapor-liquid equilibria and excess Gibbs free energies from the vapor pressure results. apparaitre que les proprietes thermodynamiques d'exces des melanges cyclopentanol + p-dioxane resultent principalement de la rupture de la structure du solvant p-dioxane, dans ces melanges.