Place butter in microwave safe bowl. Place bowl in microwave and melt butter (15 to 30 seconds on high). Add Old Bay seasoning (TM) and lemon juice. Stir well.
Coat microwave safe pan with non-stick cooking spray. Arrange shrimp in a layer in the pan. Pour butter mixture evenly over shrimp.
Cook in microwave on high power for 6 minutes. After two minutes have elapsed pause microwave and rearrange shrimp (move shrimp for the center to the outside, from the outside to the center). Let the shrimp cook another 2 minutes. When 4 minutes have elapsed pause the microwave again, rearrange the shrimp once more. Place shrimp back in the microwave and cook remaining two minutes. Cook until shrimp turn pink. Serve hot with your favorite cocktail sauce.