The catalytic performance of the microporous titanosilicate ETS-10-type catalysts for the aldol condensation of acetone has been investigated and compared with that of zeolite-X-type materials. The reaction was carried out on as-prepared, potassium- and cesium-exchanged and cesium oxide-impregnated catalysts. It is shown that this reaction may be catalysed by both acidic and basic sites and the product distribution depends, to a great extent, on the acid-base properties of the catalyst. The strong basicity of ETS-10 materials is manifested in this reaction process by promoting the base-catalysed condensation mode yielding remarkably high selectivities for mesityl oxides. These experimental findings highlight the potential of ETS-10 in aldol-type reactions. (C) 2000 Academic Press.