Cobalt ferrite (CoFe2O4) is a promising material due to its exceptional ferrelectric, optical, electronic and magnetic properties that are most important for device applications. The oxides with spinel structure are interesting materials responsible for useful device applications due to their promising chemical and physical properties achievable in accommodation of foreign citations. Partial substitution of iron with transition metals might play an important role to improve its different properties useful in various applications. Degree of crystallinity, particle size, electrical conductivity, optical absorption and low temperature magnetization of cobalt ferrite were measured before and after doping with transition metals Zr, Zn and Cd. The crystallinity improved for doping effect. The charge capacity and optical absorptivity also increases for doping effects. The first principle ab- initio study of on the doping effect of such transition metal elements in cobalt ferrite has been performed in this work. The bulk modulus and ductility of CoFe2O4 are 233 GPa and 0.21 where as that of CoFe1.8Cd0.2O4 are reported to 251 GPa and 0.14 respectively.