Abstract: Process of outdoor thin-layer cultivation of algae in which suspension of algae saturated with carbon dioxide and enriched with necessary nutrients, is distributed on inclined cultivation areas where the suspension of algae is distributed on inclined cultivation areas under turbulent flow which depends on velocity of flow, on coefficient of roughness of the cultivation surfaces, on the thickness of the algal suspension layer and on inclination of the cultivation surface. Between individual cultivation areas carbon dioxide is supplied into the suspension and the suspension flowing from the lowest cultivation area is conveyed into the collecting tank from which it is pumped on the upper edge of the highest cultivation area.