A new sol pillared clay is prepared by ion-exchange of Na+ ions in montmorillonite with SiO2-Cr2O3 mixed oxide sol particles, which are prepared by titrating a Cr3+ aqueous solution with NaOH in the presence of silica sol particles. Upon pillaring of oxide sols, the basal spacing of montmorillonite is expanded up to 47 Angstrom and the porous textures of pillared compounds are retained at least up to 700 degrees C. In spite of large interlayer separation, the pillared clay exhibits characteristic adsorption behavior of microporous solid with a large BET surface area of 420 m(2)/g. The temperature-programmed-desorption spectra of ammonia revealed that the sample calcined at 400 degrees C has bath strong Bronsted and weak Lewis acid sites, whereas the sample heated at 600 degrees C shows significant Lewis acidity due to the formation of a new Si-O-Cr Linkage.