Grilling bakes the potatoes in their jackets. Make sure that you pierce each potato before grilling them so they don't explode while they are on the grill.
Preheat a grill to medium-high heat (375 to 450 degrees).
Wash the potatoes and pierce them all over with a fork. Place each potato on a sheet of foil and brush it all over with melted butter. Wrap the potatoes in the foil, and pierce the foil several times with a fork.
Place the foil wrapped potatoes directly on grill. Cook 30 minutes, then flip them.
Cook 20 to 30 minutes more depending on the size, until tender when pierced with a paring knife
Season with additional butter, salt and pepper, or other toppings as desired.