Preheat the oven to 350 degrees F (175 degrees C). Grease and flour two loaf pans.
Combine flour, cocoa, salt, baking soda, cinnamon, and baking powder in a medium bowl and mix together. Set aside.
Cream sugar, butter, oil, and vanilla extract together in a large bowl with an electric mixer until smooth. Add eggs, one at a time, until mixed. Mix the dry ingredients slowly into the sugar mixture on medium speed until incorporated. Gently add chocolate chips, zucchini, and walnuts with a spoon. Pour batter equally into the prepared loaf pans.
Bake in the preheated oven until a toothpick inserted into each loaf comes out clean, 40 to 50 minutes. Don’t overcook.