In this experiment a novel machining methodology is presented for hardened powder tool steel (PMD23) which has better mechanical properties than conventional high speed steels. Electric discharge machining (EDM) is a non-traditional method that mainly used for extremely hard and complex shaped metals which is very difficult to machine with conventional methods. Effects of the electric discharge machining on surface roughness (Ra) and material removal rate (MRR) is experimentally studied. The selected machining parameters were current (12, 16 and 20A), pulse on time (600, 400, and 200µs) and time interval (400, 200 and 100µs). Changes on the EDM parameters result in the changes in the surface roughness and material removal rate, higher values of current, pulse on time and time interval increased the Ra and MRR.