Preheat oven to 375ºF (190ºC). Prepare 9″ x 5″ loaf pan.
Mix together oat bran and buttermilk, let stand.
Combine vegetable oil, egg and vanilla and add to bran mixture.
Combine flour, sugar, cocoa, baking soda, baking powder & salt.
Add dry ingredients to bran mixture and stir just until blended. Add chocolate chips.
Pour into loaf pan and bake 50-60 minutes or until cake tester inserted comes out clean.