High performance ceramics are increasingly used in technical applications due to their outstanding mechanical properties. With very high hardness, flexural strength and being highly wear and corrosion resistant even at temperatures above 1000°C, silicon carbide (SiC) is predestined for the area of high temperature applications. These properties however make the structuring of this material in its sintered state extremely difficult. Particularly microstructures cannot be machined by conventional methods. A process to microstructure very hard materials is electrical discharge machining (EDM), since there is no mechanical contact between tool and workpiece. With the method of assisting electrode (AE) even non-conductive ceramics can be structured. The AE provides the electrical contact for the initial discharges. By decomposition of the hydrocarbon dielectric, an intrinsic conductive layer is generated, allowing the process to sustain itself. This paper presents a study on the influence of pulse width on the EDM process of non-conductive SiC ceramic. The effect of pulse width on the anodic and cathodic removal, the present removal mechanism and on the material composition of machined structures is investigated and presented.