Lamont Perry, 26, was attacked by another inmate about 7:30 a.m. inside a dormitory at the prison in McCormick County, department spokesman Josh Gelinas said in an e-mail release. He was pronounced dead a short time later.
The Department of Corrections and the South Carolina Law Enforcement Division are investigating the attack.
Perry started serving a 15-year sentence for second-degree criminal sexual conduct in 2005. He was sentenced in Dorchester County.