In this study undoped and Co-doped ZnO films were prepared by ultrasonic spray pyrolysis technique. Co-doped ZnO films were obtained on glass substrates at different Co concentrations (at 2 %, 4 %) using zinc acetate and cobalt chloride as precursors. The effect of Co doping was investigated on the structural, optical, electrical and surface properties. The structural and physical properties of the films were studied by using X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Spectroscopic Ellipsometry, UV-VIS Spectrophotometry and four-point probe techniques. Consequently available potential of Co doped ZnO films for technological applications was searched.