Preheat oven to 150 degrees C. Line 2 baking trays with baking paper. Sift 1/4 cup sugar, cocoa and salt into a small bowl.
In a large bowl beat egg whites with an electric mixer until soft peaks begin to form. Mix in remaining 1/4 cup of sugar gradually and beat until medium-firm peaks form. Sprinkle in cocoa mixture gradually and continue beating until egg whites are stiff. Fold in chocolate chips. Drop mixture onto baking trays by rounded teaspoonfuls, spacing about 3cm apart.
Bake in preheated oven for 40 minutes for crispy biscuits. Cool biscuits on baking trays.