Mason hit 7 of 12 from the field, including 4 of 8 from 3-point range. Derrick Colter finished with 18 points and seven assists and Jeremiah Jones added 16 points for the Dukes (9-2), who have won six of their last seven games.
South Carolina State scored 10 of the game's first 14 points and led 39-38 at halftime. With the score tied at 49 with 15:41 left Duquesne went on a 16-6 run, capped by a Jones 3-pointer, to take a 65-55 lead.
Colter hit a 3 with 2:09 left to push the lead to 81-63, the highest mark of the night.
Ed Stephens scored 18 points to lead the Bulldogs (5-6).