Nitrogen and Aluminum co-doped ZnO thin films were prepared by In Situ thermal oxidation of RF magnetron sputtered Zn3N2:Al films on quartz glasses. The structural, optical and electrical properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical transmittance, photoluminescence (PL) and Hall effect measurements. XRD analyses revealed that Zn3N2:Al films entirely transformed into ZnO films after annealing in oxygen at 500 °C for one hour. Hall effect measurements confirmed p-type conduction in ZnO films with a low resistivity of 34.8Ω cm, a high hole concentration of 3.26×1017 cm-3 and a Hall mobility of 2.3 cm2/Vs. Optical transmission spectra shows that the films are highly transparent in the visible region . Our results demonstrate a promising approach to fabricate low resistivity p-type ZnO.