The micro electrical discharge machining is a novel technology applicable for the production of geometries which cannot be made by any other technologies assuming the material is electrically conductive. The machining of electrically conductive ceramics becomes possible by this way. Hole machining into these materials has high importance, however the machining parameters for the efficient and acceptable quality manufacturing are still not well discovered. In this paper authors introduce the experiments focused on learning some most important relationship between the composition of the ceramics and the machining efficiency.