Abstract: In this research, Cd1-xZnx S thin films were prepared by spray pyrolysis technique on silicon substrate at a temperature 360oC. The reverse bias capacitance for Cd1-xZnx S/n-Si heterojunciton was measured as a function of bias voltage at frequency 1MHz . The capacitance decreases with increasing of reverse bias voltage and increase with vol. of (x), it increases from 334-577 pF with increase of the (x) while the depletion width decreasing with increasing (x). We noted that these heterojunction are abrupt and the value of built-in potential decreases from 0.7-0.27 V with increasing of the ZnS vol.%. The sensitivity as a function of operating temperature in the range 100-300°C for Cd1-xZnx Sthin films were prepared by spray pyrolysis technique on glass substrate at 360°C. It is obvious that the sensitivity of all films increases with increasing of the operating temperature.