Leonard Washington added 12 points and Francisco Cruz 11 for Wyoming (4-1).
Nate Lozeau led Portland State (2-2) with 11 points.
Wyoming sank its first six shots of the second half, including two 3-pointers and a layup by Martinez, to take a 49-32 lead. Martinez, who sat out a game because of a head injury suffered in practice, swished a floater with 7:37 left that gave Wyoming a 58-38 advantage.
Portland State ended a seven-minute scoreless drought on Charles Odum’s layup at the 6:46 mark, but the Vikings were down 58-40. They would come no closer than 14 after that.