Sulfur hexafluoride (SF 6 ) strongly captures the electrons produced during an electric spark. Hence, it is used as an excellent insulating gas in high voltage electrical equipment and high power switches. The leakage of SF 6 gas reduces efficiency of such equipment and, on the other hand, it is harmful to the environment. Therefore, it is necessary to detect the gas leak as quickly as possible to prevent the failure in the electrical equipment. In this, ion mobility spectrometer was used to identify SF 6 gas. For this purpose, various atmospheric pressure ionization methods in both positive and negative modes of the spectrometer were tried. In both modes, there was no signal with UV photoionization source. Only in the negative mode with corona discharge ionization in air or nitrogen and thermal ionization sample peaks were observed. Due to the convenience, availability and higher sensitivity and stability, the optimal method for ionizing SF 6 was chosen as the negative corona in the air. The SF 6 spectrum was recorded at different temperatures from the laboratory temperature to 200 ° C. The reduced mobility, K o for the SF 6 peaks were 2.19 cm 2 /V.s and 2.08 cm 2 /V.s Comparing the results with the reported data, it was found that the ion mobility spectrum mainly contains SF 6 - ions. The optimum temperature for ionization and detection of SF 6 was obtained to be 200 ° C. The calibration curve was plotted for the SF 6 sample and its detection limit 1.79 ppm was obtained.