The goal of in this paper has to design, fabricate and test gas sensors based on chromium (Cr) doped titanium dioxide (TiO2) thin films for propane gas detection. Cr doped TiO2 thin films with different power on the Cr target ranging from 5 to 20 W were deposited by confocal magnetron sputtering at same deposition conditions. The effect of Cr concentrations on structural, morphological and optical properties of the films have been investigated in detail. The thin film characterizations were performed by using X-Ray Photoelectron Spectroscopy (XPS), Energy-Dispersive X-Ray Spectroscopy (EDX), Secondary Ion Mass Spectroscopy (SIMS), Atomic Force Microscope (AFM), UV-Vis-NIR spectrometer and Photoluminescence (PL) systems. The sensing behavior of the sensors was tested with gas testing system to propane gas at 250, 500 and 1000 ppm. The high sensor performance was observed in gas detection behavior with increasing Cr content. In particular, the obtained gas sensor with Cr RF power of 20 W exhibited higher sensor response in the detection of propane at working temperature of 300 degrees C.