The porous siloxane thin film containing nanopores (< 5.0 nm) can be effectively prepared by using-an acyl mono/di-saccharide compound through porogen templated approach. The saccharide compound used as a porogen in this study effectively made pores in the siloxane thin film through their decomposition during hard curing process. The saccharide compounds seem to be assembled into adequate domain size in the silsesquioxane polymer via the intermolecular interaction between acyl groups of the porogens. The pore diameter of porous siloxane film prepared with 30 wt.% of benzoyl sucrose in spin-coating solution was 2.2 nm based on positronium annihilation lifetime spectroscopy. The saccharide derivatives templated nanoporous siloxane thin films showed the low dielectric property (k < 2.5). (c) 2004 Elsevier B.V. All rights reserved.