In bowl, stir together oil, garlic, paprika, pepper, mustard, oregano, chili powder, onion powder, salt and cayenne pepper.
Cut salmon into 1 1/2 -inch chunks; add to bowl and toss gently to coat evenly. In separate bowl, toss together scallops and pinch each salt and pepper. Alternately thread salmon and scallops onto soaked wooden skewers.
Place kabobs on greased grill over medium heat; close lid and grill, turning once, until scallops are opaque and fish flakes easily when tested with fork, about 6 minutes.