A natural clay (henceforth referred as T1) was pillared with aluminum (A1-PILCT1) and then both clays were impregnated with either cobalt nitrate or cobalt acetate. The basal spacing, the surface area, the acidity and dispersion of these solids were determined by X-ray powder diffraction,N-2-BET, cyclohexylamine adsorption methods and CO chemisorption, respectively. An increase in the basal spacing and the surface area in the pillared and impregnated solids from T1 were observed, i.e., from 9.9 to 17.0 Angstrom and 75 to 184 m(2) g(-1), respectively. The catalytic activity of these materials was measured using the dehydrogenation of ethylbenzene to styrene as a test reaction, at 400degreesC for 1 h. The total conversion for this reaction was <20% in all cases, being the conversion of the Co-impregnated natural clays higher than natural, Al-pillared and Co-impreanated Al-pillars clays. The catalytic activity is directly related to the cobalt content in the prepared materials. (C) 2003 Elsevier B.V. All rights reserved.