The transformation of cyclopentanol and cyclohexanone mixture at 250 degrees C makes it possible in simple reaction to consider the acidic and basic properties of catalysts. Two reactions take place: the hydrogen transfer on basic sites and the alcohol dehydration on acid sites. These reactions were used to compare the different crystallographic phases of alumina: eta to alpha. From these reactions, we show that aluminas can be divided into two groups: (1) theta and alpha, which possess a basic character close to the one observed on MgO, and (2) eta, gamma and delta, which appear less basic, and possess an acidic character. (C) 2008 Elsevier B.V. All rights reserved.