Spray a grill rack with nonstick nonflammable cooking spray. Preheat the grill to medium-high heat, 350 to 400 degrees F.
Beat the butter, cilantro, salt and pepper in a small bowl with a fork until smooth. Spread about 1 tablespoon of the butter mixture over each half ear of corn. Wrap the corn in heavy-duty aluminum foil. Grill, turning frequently, until the corn is tender, 18 to 20 minutes. Serve immediately.