Preheat oven to 325F.
Butter and flour 13 x 9 x 2-inch pan.
Sift flour, cocoa powder, soda and salt into medium bowl.
Beat sugar, butter and oil in large bowl until well blended.
Add eggs 1 at a time, beating well after each addition.
Beat in vanilla extract.
Mix in dry ingredients alternately with buttermilk.
Mix in zucchini.
Pour batter into pan.
Sprinkle chocolate chips over.
Bake cake about 50 minutes (or until cake tester comes out clean).
Cool cake completely in pan.