We report the sol–gel preparation of SiO 2 / montmorillonite composite materials and the investigation of the effect of the amount of clay and the TEOS concentration on the textural and structural properties of the composites. Pre-swelling of the clay with cetyltrimethyl ammonium results in solids with a larger mesoporous surface area. A decrease in the gel time and an increase in the surface area were observed upon increasing the amount of clay in the reaction medium. These porous solids showed acidic properties, and their acidities were correlated with the amount of the clay mineral. The obtained composites were functionalized by adding manganese, and their catalytic properties were evaluated in the cyclohexene oxidation reaction. Graphical Abstract & Tesnime Abou Khalil tttesnime@yahoo.fr