Sour John is a census-designated place (CDP) in Muskogee County, Oklahoma, United States.

Sour John is immediately to the east of Greenleaf Lake and north of Oklahoma State Highway 10.

[4] According to the United States Census Bureau, the CDP has a total area of 5.7 square miles (15 km2), all land.

17.4% of all households were made up of individuals, and 8.7% had someone living alone who was 65 years of age or older.

There were 15.0% of families and 13.4% of the population living below the poverty line, including 10.0% of under eighteens and none of those over 64.