Preheat oven to 350°F. Spray bottom of 8x4 inch loaf pan with cooking spray. Beat sugar, eggs & oil in large bowl at medium speed until combined. Beat in banana & vanilla at low speed. Combine flour, cocoa, & baking soda in medium bowl; beat into banana mixture at low speed, just until combined. Stir in chocolate chips.
Spoon batter into pan.
Bake 60 to 70 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes. Remove from pan; cool completely on wire rack.