Unsweetened baking chocolate contains 50 to 58 percent cocoa butter. Bitter in flavor, it's used primarily in baking. You'll find it in the supermarket in a rectangular box containing packages of one-ounce squares or bars.
Dried chocolate liquor, with the cocoa butter removed, is ground into unsweetened baking cocoa. Cocoa drink mixes that contain added powdered milk and sugar should not be used for baking cocoa.