Place the shucked ear of corn in the center of the aluminum.
Spread 1-2 tablespoons butter or margarine along the length of the corn.
Heavily sprinkle garlic salt and pepper over the piece of corn.
Move the ear of corn down to an edge of the aluminum and tightly roll the ear of corn in the aluminum foil being sure to tightly twist the ends to hold in the butter.
Repeat for each ear of corn.
Place corn on hot grill for 20 minutes, occasionally turning.
Remove from grill and allow to cool slightly before serving.