CeO₂ & Ag⁰ and TiO₂ & Ag⁰ nanocomposite particles formed as a result of co-precipitation were analyzed using XRD, CEM, and EDS methods. Heating the precursor in the temperature range from 400 to 600 °C allows to obtain on their surface a homogeneous phase of cerium and titanium dioxide (anatase) modified with silver clusters. Heat treatment causes particle size reduction. The general mechanism of the phase formation process is closely related to the direct red-ox reaction between trivalent cerium or titanium and silver cations without reducing agents adding.