Adelphi is a village in Ross County, Ohio, United States.

[6] According to the United States Census Bureau, the village has a total area of 0.27 square miles (0.70 km2), all land.

The racial makeup of the village was 95.0% White, 1.6% African American, 0.3% Asian, and 3.2% from two or more races.

29.2% of all households were made up of individuals, and 11.6% had someone living alone who was 65 years of age or older.

The racial makeup of the village was 96.23% White, 2.96% African American, and 0.81% from two or more races.

26.3% of all households were made up of individuals, and 12.2% had someone living alone who was 65 years of age or older.