Radium is a city in Stafford County, Kansas, United States.

[3] A post office was opened in Radium in 1910, and remained in operation until it was discontinued in 1990.

[4] According to the United States Census Bureau, the city has a total area of 0.04 square miles (0.10 km2), all of it land.

[5] The 2020 United States census counted 26 people, 13 households, and 7 families in Radium.

There were 16 housing units at an average density of 390.2 per square mile (150.7/km2).

30.8% of households consisted of individuals and 15.4% had someone living alone who was 65 years of age or older.

41.2% of all households were made up of individuals, and 11.8% had someone living alone who was 65 years of age or older.

The community is served by Macksville USD 351 public school district.