Kay County is a county located in the U.S. state of Oklahoma. As of the 2010 census, the population was 46,562. Its county seat is Newkirk, and the largest city is Ponca City.Kay County comprises the Ponca City, OK Micropolitan Statistical Area. It is in north central Oklahoma on the Kansas state line.Before statehood, Kay County was formed from the “Cherokee Strip” or “Cherokee Outlet” and originally designated as county “K.” Its name means simply that.