Preheat grill to high.
In a small bowl mix the sugar, vinegar, oil, and mustard. Set up skewers with ham and pineapple alternating.
Set prepared skewers on a large platter or baking pan with sides. Brush skewers with prepared sauce.
Place skewers on the grill and cook about 8-10 minutes turning often and basting several more times as they cook.