Abstract: An apparatus for electroerosion within a solid component which includes a hollow stationary cylinder, a control rod surrounded by and coaxial with the cylinder, a driving square terminating one end of the rod and an electrode connected to said driving square. The electrode is pivotable around an axis perpendicular to the axis of the cylinder, movable together with the rod along the axis of the cylinder, positionable perpendicular to the axis of the cylinder and rotatable around the axis. The method comprises machining a pilot channel in the solid component having a cross-sectional identical with the aperture cross-section of the proposed cavity, introducing an electrode into the channel, moving the electrode relative to the solid component and removing material from the cavity so formed in the solid component.