Zn0.90Co0.10O particles, synthesized by mechanical milling and thermal treatment, were pressed at 25 tons to form a 2” target for a radio frequency (r. f.) magnetron sputtering system. Using this target, thin films were deposited on (0001) oriented sapphire (α-Al2O3) substrates under 30W, 60W and 120W r. f. powers. Structural analyses of these films were done with X-Ray Diffractometer (XRD), Energy Dispersive X-Ray Spectrometry (EDS), X-Ray Photo Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The ZnO films were deposited with (0002) preferred direction, which was coherent to (0001) ordered α-Al2O3. Impurity phases, such as Co clusters, CoO and Co3O4, were not detected with the surface analyses of Zn0.90Co0.10O thin films. Substituted Co atoms in the host ZnO matrix were identified by the binding energy peak of Co2p3/2, 781.3±0.4eV, and the energy difference of ∼15.61±0.03eV between Co2p1/2 and Co2p3/2. These results also proved that there were no Co clusters or Co3O4 phases in the lattice. Homogeneity of Co atoms in the lattice was shown by EDS spectra. It was understood that the higher r. f. power caused the more homogeneous distribution of Co and Zn atoms in thin films. Distributions of Co and Zn on the film surface, deposited under 120W, were found as 8.1±0.1% (normalized atomic ratio) and 91.7±0.7% (normalized atomic ratio), respectively, and the surface roughness of thin film was demonstrated by AFM figures as 14.2±0.1nm.