Co-Ga co-doped ZnO films were fabricated by pulsed laser deposition on quartz substrates. The obtained films exhibited a wurtzite structure with c-axes growth preference. Optical measurements showed the presence of the cobalt ions in a tetrahedral crystal field, which proved that the Co ion substitution in the ZnO lattice, acting as magnetic cation. Hall measurements indicated that the films were n-type conductive with the electron concentrations of similar to 10(20)/cm(3). This value was much higher than that of the Co-doped films, suggesting the effective incorporation of Ga in the films. Room temperature ferromagnetism was observed for the Ga-Co co-doped thin films. (C) 2009 Elsevier B.V. All Fights reserved.