The invention provides a method for determining the position of a channel which has been electrochemically machined in a workpiece by an electrolyte and/or the wall thickness which is present between the electrochemically machined channel and the surface of the component, in which magnetic particles are added to the electrolyte used during the machining, the magnetic fields associated with the magnetic particles are detected, and the position of the electrochemically machined channel and/or the wall thickness which is present between the electrochemically machined channel and the surface of the component is determined on the basis of the detected magnetic fields.