p.s. whenever you ask a recipe question, it's better to link or explain the recipe.

Also, if you're using cocoa in place of choc chips in a cookie or cake, you can't do that w/o looking into the affect on the consistency and moistness of the item. It's equivalent to using nut flour instead of chopped nuts.

This is a truly intriguing question. It really depends on the recipe. I love that *FoodIsLove* said, "3 Tablespoons of sifted cocoa powder to 1 Tablespoon of neutral oil (think canola or safflower) = 1 ounce of unsweetened chocolate. For semisweet chocolate use 3 tablespoons of cocoa plus only 1 1/2 teaspoons of oil and 1 to 1 1/2 tablespoons of sugar (depending on how sweet you want your semi-sweet to be," But I disagree with the dutch vs. natural cocoa powder part.
Cocoa powder varies in so many kinds of ways, as do "chocolate chips," that without seeing a recipe/method, I don't believe there's a true "ratio."

3 Tablespoons of sifted cocoa powder to 1 Tablespoon of neutral oil (think canola or safflower) = 1 ounce of unsweetened chocolate. For semisweet chocolate use 3 tablespoons of cocoa plus only 1 1/2 teaspoons of oil and 1 to 1 1/2 tablespoons of sugar (depending on how sweet you want your semi-sweet to be. Also, use natural cocoa powder not Dutched as the alkaline in the Dutched might effect the leavening in the recipe. I assume the recipe melts the chocolate chips? One final note, most chocolate chips have lecithin in them as a stabilizer; not sure if this matters.

What is the recipe?