1. Heat oven to 400 degrees F. Coat a baking sheet with vegetable cooking spray.
2. Wash potatoes. Cut into thin slices, and place in large bowl. Pour oil onto the palms of your hands. Gently rub oil onto sweet-potato slices, tossing to combine. Sprinkle with sugar and cinnamon, tossing in bowl to coat evenly.
3. Place slices in a single layer on prepared baking sheet. Bake 20 minutes. Turn chips over and bake until slightly crisp, about 5 minutes. Transfer to plate; cool 5 minutes and serve.