A forming tool and a forming method for producing an overpressure predetermined breaking point in a battery cover by deformation. The forming tool has a stamping tool and a die tool and an optional hold-down arrangement. On the die tool a support surface is provided for the battery cover to be deformed to form a forming cavity in the die tool in a depressed manner. On the stamping tool a stamp part and a ring-shaped stamp part is provided corresponding to a bead to be created in the battery cover in the cross-section. During deformation of the battery cover the stamping tool is pressed in the battery cover, whereby material of the battery cover flows into the forming cavity. Thereby the stamping tool is approached to the forming cavity in a manner such that the remaining distance corresponds to a minimum wall thickness at the overpressure predetermined breaking point.