In a shallow glass dish, mix the soya sauce, brown sugar, sherry, sesame oil, ginger and garlic. Stir the chicken pieces and pineapple into the marinade until well coated. Cover, and marinate in the refrigerator at least 2 hours.
Preheat barbecue to medium-high.
Thread chicken and pineapple alternately onto skewers.
Cook on the barbecue 15 to 20 minutes, turning occasionally, or until chicken juices run clear.