Preheat your oven to 350°F (175°C) and grease a loaf pan.
In a bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.
In a separate bowl, mix the sugar and vegetable oil. Add the eggs one at a time, mixing well after each addition. Then stir in the vanilla extract, orange zest, orange juice, and buttermilk.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the chocolate chips.
Pour the batter into the prepared loaf pan and bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.:
Slice and enjoy your delicious chocolate orange loaf cake!