Sulphur is a city in Murray County, Oklahoma, United States. The population was 4,794 at the 2000 census. It is the county seat of Murray County.
Sulphur is located at 34°30′33″N 96°58′31″W / 34.50917°N 96.97528°W / 34.50917; -96.97528 (34.509159, -96.975371).
According to the United States Census Bureau, the city has a total area of 7.0 square miles (18.0 km²), of which, 6.8 square miles (17.7 km²) of it is land and 0.2 square miles (0.4 km²) of it (2.16%) is water.