A mixing capsule, especially for the production of dental materials, comprises a cartridge that is closed on one end by a piston. The piston has a hemispherical recess that forms a secondary chamber and is closed off from the main chamber of the cartridge by a separating device. A body that is provided in the initial state in the main chamber is used to facilitate the mixing process and to penetrate the separating device at the beginning of the process, whereby the main chamber and the secondary chamber form a single mixing area. The body preferably disintegrates during the mixing process.