Although several studies have explored the rGO-ZnO nanocomposites gas sensing properties towards many gases,only a few are devoted to ozone detection. This paper explores a novel synthesis procedure of rGO-ZnO nanocomposites based upon a two-step physical process. Namely, a reduction process of GO carried out using UV laser radiation followed by a deposition of ZnO nanoparticles on the rGO surface by RF-magnetron Sputtering. Our results demonstrate that the deposition of ZnO on the surface of the rGO film produces a stable and conductive material with a larger surface area. Consequently, this material is able to operate at high temperatures and exhibited a limit of detection (LOD) in the range of 100 ppt while pure ZnO exhibited LOD in the vicinity of 1 ppb.