Saint Theoctistus founded a monastery in the city of Cucomo on the island of Sicily, where he became igumen. At his monastery were some Greek monks who fled persecution by the iconoclasts. He died in the year 800.
Saint Theoctistus of Sicily should not be confused with Saint Theoctistus of Palestine (September 3), the companion of Saint Euthymius (January 20) in the ascetic life.