In this paper, dry electro-discharge machining (Dry EDM), one of the newest machining processes which differs mainly from conventional EDM in using gaseous dielectric along with tool electrode rotation, has been studied. Gap voltage, discharge current, pulse-on-time, pulse-off time, dielectric gas pressure, and electrode rotational speed have been considered as effective input parameters. Response surface methodology (RSM) has been used to optimize the machining performance with respect to material removal rate (MRR). Base on the results and analysis of running experiments, it can be concluded that MRR increases by increasing gap voltage, discharge current, the ratio of pulse-on time over pulse-off time, input gas pressure, and electrode rotational speed. There also exists an optimum amount of pulse-on time determined according to the machining circumstances. Also the material removal rate in dry EDM has been improved compared with that in conventional EDM in identical conditions. Keywords: Dry electro-discharge machining (Dry EDM), Gaseous dielectric, Response surface methodology (RSM) Keywords: Dry electro-discharge machining (Dry EDM), Gaseous dielectric, Response surface methodology (RSM) Keywords: Dry electro-discharge machining (Dry EDM), Gaseous dielectric, Response surface methodology (RSM)