Preheat the oven to 375°F with a rack in the center position.
In a small bowl, combine the brown sugar, salt, paprika, garlic powder, and pepper.
Place the salmon on a rimmed baking sheet, skin side down. Brush the salmon with the olive oil, then rub it with the spice mixture until completely coated.
Bake for 12 to 15 minutes (depending on thickness), or until the fish flakes easily with a fork.