Xenia is a city in and the county seat of Greene County, Ohio, United States. The municipality is located in southwestern Ohio 21 miles from Dayton and is part of the Dayton Metropolitan Statistical Area. The name comes from the Greek word Xenia, which means "hospitality". Many of its residents supported the Underground Railroad in the years before the Civil War. As of the 2010 census, the city had a population of 25,719. Xenia is the third largest city in Greene County, behind Fairborn and Beavercreek.