The intercalation of a saponite with the Al polycation [Al13(OH)24(H2O)24]15+ is described. This polycation is obtained by reaction of alumina with Al chloride. The intercalation is achieved by reaction of very concentrated solutions of this polycation with the clay in powder form. Solids with a basal spacing of 18.9 Å were obtained in this way, stable up to 700°C (17.0 Å). The Langmuir surface area of the intercalated solid was 366 m2/g, and that value decreases to 119, 138 and 125 m2/g for the solids pillared at 500, 600 and 700°C, respectively.