The objects of the present invention are to provide core-shell type cobalt oxide microparticles, a dispersion containing such microparticles, and a production process and uses of the microparticles and the dispersion, and the invention is directed at: core-shell type cobalt oxide microparticles having an average particle diameter of from 50 to 200 nm, wherein the core is a secondary particle of spherical shape to a surface of which an organic polymer is attached as the shell; a dispersion of such cobalt oxide microparticles; a dry powder obtained from such a cobalt oxide microparticle dispersion; a process for producing core-shell type cobalt oxide microparticles or a dispersion thereof, which process includes the steps of: mixing together a cobalt salt and an organic polymer in an organic solvent so as to obtain a mixture; and heating/refluxing the mixture at a predetermined temperature so as to cause core-shell type cobalt oxide microparticles to precipitate, wherein the cobalt salt is cobalt acetate; and uses of the cobalt oxide microparticles, the dispersion and the dry powder.