This paper reports investigations on the formation of hydrogen peroxide resulting from micro-pulse plasma discharges obtained in pin-to-pin configuration underwater. In particular, this study reports the influence of the discharge regime (cathode regime with and without breakdown, and anode regime) as well as that of the discharge energy (from 10 to 45 mJ per pulse). It has been shown that the H2O2 production is higher for high energy and anode regime. In addition, the variation of the pulse width (from 50 to 500 mu s) highlights the dependence of the chemical processes induced by the discharge according to the regime. Considering two different electrode materials (tungsten and platinum), we do not observe any significant influence of the electrode material on the H2O2 production, whereas the injected energy depends on the high voltage electrode material. Finally, the erosion of the electrodes have been studied using in-situ optical microscopy and SEM. It is shown that the erosion mechanisms strongly depend on materials, regimes and the polarity of the electrodes.