Co doped ZnO films were synthesized from the precursors Zn(CH 3COO) 2.2H 2O and Co(CH 3COO) 2.4H 2O by using a "High Voltage Spray Pyrolysis" technique. The physical properties of the prepared films were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and physical property mesurement system (PPMS) measurements. The films studied were of a wurtzite phase with grain sizes of about 20 nm. The 5 % Co-doped ZnO films exhibited ferromagnetic behavior at room temperature. The transmission and the optical magnetic circular dichroism (MCD) measurements confirmed that Co 2+ was located at the tetrahedral sites of the ZnO wurtzite structure. MCD results showed that the observed ferromagnetism was less likely related to a carrier-induced mechanism.