Polysilsesquioxanes were prepared through the acid-catalyzed hydrolytic polycondensation of triethoxy(methyl)silane, triisopropoxy(methyl)silane, or triisobutoxy(methyl)silane and subjected to dip coating to form coating films. The film formation depended on the polarity and crystallinity of the substrate, and a correlation was found between the substrate and polysilsesquioxane solubility parameters. When the coating film was heated, thermal condensation occurred at about 500 degreesC between hydroxy groups or between hydroxy and alkoxy groups. The methyl group attached to silicon decomposed, and siloxane bonding formed at about 800 degreesC. The adhesion and hardness of the coating films were evaluated with the Japanese Industrial Standard K5400 protocol, and they increased with increases in the heating time and heat-treatment temperature. The refractive index of the coating films decreased when the heat-treatment temperature was increased to 500 degreesC because of the combustion of organic groups. In contrast, the surface electric resistance increased with the heattreatment temperature up to 500 degreesC. The dielectric constant was 2.6-2.8 and decreased with an increases in the molecular weight and the degree of crosslinking of the polysilsesquioxanes. (C) 2004 Wiley Periodicals, Inc.