Abstract: The present invention relates to the field of single-use closed capsules biodegradable by industrial composting and by domestic composting, containing at least one substance in powder form for the preparation of a drink, e.g. coffee, intended for being extracted under pressure, said capsule including a container with a bottom and a side wall having a circular rim, and a seal welded on the circumference of the rim of the container, characterized in that the bottom, the side wall and the circular rim are formed by injection molding of at least one formulation comprising: (i) at least one polymer chosen from polyhydroxybutyrates, and (ii) at least one ingredient chosen from silicates, vitamin E, plasticized proteins of animal or plant origin, or mixtures thereof.