In a medium bowl, stir together the olive oil, ranch dressing, Worcestershire sauce, rosemary, salt, lemon juice, vinegar, pepper and sugar. Let stand for 5 minutes. Place chicken in the bowl and stir to coat with the marinade. Cover and refrigerate for 30 minutes.
Preheat the barbecue for medium-high heat. Thread chicken onto skewers and discard marinade.
Lightly oil the cooking grate. Barbecue skewers for 8 to 12 minutes or until the chicken is no longer pink in the centre and the juices run clear.