Abstract: A mixing capsule for a two-component mixture comprises a preferably cylindrical container part. An axially displaceable piston is guided within the container part. An opening is provided on the front face of the piston and leads into a liquid receptacle with a burstable wall or membrane. The membrane closes the opening in the non-activated condition of the capsule. The hollow between the front faces of the container part and the piston constitutes a mixing chamber. The activation part can be displaced by means of activation pin that closes the discharge nozzle in the non-activated condition. In the activated condition of the capsule the activation part is to all intents and purposes completely accommodated within the liquid receptacle.