Electrically conducting latexes of polypyrrole coated on inorganic cores were obtained by deposition of pyrrole on catalytically active particles. The finely dispersed core materials were hematite (polyhedral and spindle-type), silica coated with hematite, magnetite, and cerium(IV) oxide. The degree of polymer coverage could be controlled by varying the aging time and the properties of the carrier particles. Also, yttrium basic carbonate was coated on polypyrrole latex. The so prepared coated powders were examined by transmission electron microscopy, and further characterized by elemental and thermogravimetric analyses, as well as by electrophoresis, X-ray diffraction, and conductivity measurements. The d.c. conductivities of all but the magnetite particles coated with polymer were comparable to those reported for pure polypyrrole and they increased with pressure.