This work describes the synthesis, characterization and catalytic properties of montmorillonite pillared with mixed aluminum/lanthanum pillars. This material presents characteristics that are very different from montmorillonite pillared only with aluminum. It shows a bimodal micropore structure, through generation of pores at the limit between microporosity and mesoporosity. The textural parameters show higher values and it is thermally more stable, maintaining high values of specific surface area and micropore volume up to 700 degrees C. The acidity of aluminum/lanthanum pillared material reveals that its surface shows more acid centers, mainly Lewis-type. The increase of the conversion in dehydration of 1-butanol as in hydroisomerization of heptane shows its better behavior as an acid catalyst. The study of 1-butanol dehydration shows that there is an increase in the acidity and the thermal stability and a smaller deactivation by carbonaceous deposits in the aluminum/lanthanum pillared material. (c) 2006 Elsevier B.V. All rights reserved.