Preheat a grill to medium high and brush the grates with vegetable oil. Toss the chicken with the olive oil, lemon juice, thyme, garlic, 1/2 teaspoon salt and a few grinds of pepper in a large bowl. Thread onto eight 10-inch skewers along with the peppers.
Grill the kebabs, covered, turning occasionally, until the chicken is cooked through and the peppers are charred, about 10 minutes.