Micro electric discharge machining (μ-EDM) process is being used to machine complex shapes on silicon. In specific, dry-μ-EDM can be used to process assembled or semi assembled silicon products. However, there is lack of investigation on the effect of single pulse discharge machining and its plasma characteristics on silicon. Hence, in this paper we investigate the crater and plasma characteristics of single discharge for various conditions such as different electrode diameters and different energy conditions (fixed voltage with varying capacitance and vice-versa). The plasma temperature and electron density have been calculated by line pair method and modified Saha equation respectively. The values are mapped into the plasma classification plot based on log scale of plasma temperature and electron density and realised that at μ-scale EDM plasma was found to be ideal up to 50 mJ energy and tends to become weakly non-ideal plasma for 98 mJ energy. Also from the influence of energy on plasma characteristics it is understood that electron density also plays a major role along with the plasma temperature. © 2012 Inderscience Enterprises Ltd.