We report a systematic study of structural, optical, and magnetic measurements on Zn0.9Cd0.1S:yCo films in the concentration range of 0.005 ≤ y ≤ 0.05 M using pulsed laser deposition technique. Structure, composition analysis, and optical measurements revealed that Cobalt is incorporated into the lattice, as Co2+ substituting Zn 2+ ions, forming a solid solution with cubic structure instead of Cobalt precipitates. Low temperature magnetization measurements reveal a paramagnetic behavior. UV-vis measurements showed a red shift with respect to undoped sample in the energy band gap with increasing Cobalt concentration. Photoluminescence measurements shows ∼ 300 times increase in intensity by Cobalt doping in Zn0.9Cd0.1S matrix. © 2011 Elsevier B.V.