Bismuth silicon oxide Bi12SiO20 (BSO), which has a sillenite structure, is a piezoelectric, electro-optic, photo-refractive, and optically active material. Recently, the sillenites have begun to be considered for use as dielectric in the field of electronics. They are used as new material in LTCC (Low-temperature co-fired ceramic) technology. Because of the low sintering temperature, good chemical and dielectric properties of the “bulk” BSO1 we decided to prepare thin films of this material. In this paper we will report on the preparation of BSO thin films using sol-gel method on various substrates. The aim of work was to achieve pure BSO thin films with good control over their microstructure and thickness.