In recent papers it is considered that the catalytic behavior of the lanthanide oxides is closely related to the properties of Ln 3+ ions [1, 2]. In particular, for alcohol decomposition reactions, a regular variation ▪ of activity from La 2O 3 to Lu 2O 3, parallel to the ionic radius of Ln 3+ is proposed both for dehydration and for dehydrogenation processes [1, 3]. Our results are not in accordance with these ideas [4, 5]. Other aspects like those related to the textural properties of the oxides play an important role, having a significant influence on both the activity and product distribution data. This point is discussed in the present paper. The catalytic activity has been measured for a series of six lanthanides sesquioxides, La, Sm, Eu, Dy, Ho and Yb, and for CeO 2. All these oxides have been prepared, according to [6], by calcination of the corresponding hydroxide phase. The BET surface area of Yb 2O 3(HYD), 54 m 2 g −1, changes to 5.5 m 2 g −1 after a grinding process (sample GR). By calcination of ytterbium oxalate an Yb 2O 3, (OXA), with 24 m 2 g −1 was obtained. A commercial MERCK AR sample, (COM), with BET surface of 8.5 m 2 g −1 is also considered. The decomposition of 2-propanol and 2-pentanol was studied in a differential flow reactor at normal pressure. Some additional details are given in [5]. Results and Discussion According to Fig. 1 the specific activity of Yb 2O 3(GR) is about 12 times higher than that existing among the series of Ln 2O 3. The difference of activity between both Yb 2O 3 samples does not depend on the temperature (experimental range 600–750 K) and therefore grinding does not cause differences in the selectivity (% dehydration). t001 Product Distribution Data for 2-Pentanol Decomposition, at 698 K, over Different Yb 2O 3 Samples. The limit values for the series of sesquioxides are included. % Dehydration % 1-Pentene Cis/Trans Yb 2O 3(Hydroxide) 86 84 1.7 Yb 2O 3 (Oxalate) 88 94 0.6 Yb 2O 3 (Commercial) 86 89 1.2 Minimum 72 (La 2O 3) 78 (Sm 2O 3) 0.7 (Ho 2O 3) Maximum 87 (Ho 2O 3) 94 (Ho 2O 3) 1.7 (Sm 2O 3) ▪ For 2-pentanol decomposition, Fig. 2, the influence of the preparation method on the activity of Yb 2O 3 samples is rather similar or even greater than that observed throughout the series of sesquioxides. This is so even in the case of considering the activity data for CeO 2, an oxide with quite different general properties from those of Ln 2O 3. With regard to selectivity data (Table I) for dehydrogenation-dehydration, as in the case of 2-propanol, no differences are observed among the ytterbia samples. On the contrary, for % 1-pentene and cis/trans ratios the variations are rather analogous to those observed for the sesquioxides. The study of the textural properties of Yb 2O 3(HYD) and Yb 2O 3 (GR) shows notable differences to each other, the latter one being an essentially nonporous sample. This suggests that the fraction of the total surface area corresponding to the narrower pores has a minor contribution to the overall reaction rate, which would be more closely related to the external surface area than to BET surface. When Fig. 2 is analysed, it can be deduced that the preparation method affects not only the effective surface area but also, as % 1-pentene and cis/trans ratio changes show, the distribution of centers participating in the dehydration reactions.