Abstract: An electrode tool for the electrochemical machining of metal components, such as the cavities of internal combustion engine valves, is adapted for mounting on a machine tool mandrel and comprises a shaft upon which a flexible, elongate electrode is axially slidable, and which defines axially a conduit for conveying electrolytic fluid to the workpiece. The working end of the tool is constituted by a releasable electrode guide head which defines a part-circularly-curved electrode guide passage and the end portions of the conduit. The guide passage guides the axial sliding of the electrode so that an end portion of the latter projects radially relative to the axis of the tool by an angle determined by the radius of curvature of the passage. The guide head is interchangeable with at least one other guide head having a passage with a different radius of curvature.