A Colombian montmorillonite was successfully pillared with solutions of Al, Al-Zr, Zr and Al-Si polyhydroxocations to obtain active catalysts for the hydroconversion of n-heptane. The catalysts were characterised by X-ray diffraction, N-2 adsorption and heptane hydroconversion tests. The catalysts modified by mixed pillaring (Al-Zr and Al-Si) showed a favourable effect on the activity, selectivity and stability, leading to an increase in heptane isomer products. (c) 2005 Elsevier B.V. All rights reserved.