Ultrafine layered potassium tetratitanate K2Ti4O9 powders were prepared by solid-state reaction using nanometer sized TiO2 as the reactant. The structures of the titanates and the products which had undergone H+ exchange and intercalated by propylamine and [Al13O4(OH)(24)(H2O)(12)](7+) (Al-13(7+)) were investigated by XRD, TEM, TG and BET analysis. Compared with the larger-sized products prepared by using micrometer sized TiO2, the ultrafine K2Ti4O9 takes in more intercalating molecules, which leads to the expanding of the interlayer distance of the resulting products. The final Al2O3 pillared Ultrafine tetratitanate exhibits higher BET surface area (212.8 cm g(-1)) and narrow pore-size distribution. (c) 2005 Springer Science + Business Media, Inc.