Metal-nitrogen-carbon (MNC) cathode catalysts were synthesized using nitrogen precursors of varying Nitrogen/Carbon (N/C) ratio by pyrolysis in a constant volume reaction vessel. Here, we demonstrate that increasing a key property, the N/C ratio of the nitrogen precursor increased the accessible active site density by reducing carbon deposition in the pores of the carbon support during pyrolysis. The most active catalysts were obtained in this work using melamine, having a N/C ratio of 2. Kinetic current density as high as 13 A cm(-3) at 0.8 ViR-free and over 100 h of stable current at 0.5 V were observed with melamine based MNC catalysts. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3566065] All rights reserved.