Scioto County is a county along the Ohio River in the south-central part of the U.S. state of Ohio. At the 2020 census, the population was 74,008. Its county seat is Portsmouth. The county was founded on March 24, 1804, from Adams County and is named for a Native American word referring to deer or deer-hunting. Scioto County comprises the Portsmouth, OH Micropolitan Statistical Area. It is at the confluence of the Scioto and Ohio rivers.