An iron-rich saponite, variety griffithite, from Griffith Park, California, USA, has been pillared with hydroxy-aluminium oligomers, giving rise to very crystalline layered solids with basal spacings of 17.4-17.7 a and specific surface areas of 233-293 m(2)/g. The catalytic performance of these pillared solids, and also of the natural griffithite, all after calcination at 773 K, in the dehydrogenation of ethylbenzene was evaluated. The catalytic behaviour strongly depends on the acid properties developed in the solids by the pillaring treatment.