Copper(II) pentafluoropropionate and heptafluorobutyrate adducts with 1,4-dioxane, tetrahydropyran, and tetrahydrofuran have been prepared and characterized by means of magnetic-susceptibility and IR-spectroscopy measurements. The variation in their magnetic moments is discussed in terms of the acidity of the parent acid and the hyperconjugative effect of the fluoroalkyl group.