Porous carbon materials with varying structural and compositional properties were studied for their impact on the nitrogen content and activity of metal-nitrogen-carbon (MNC) oxygen reduction catalysts prepared using high-pressure pyrolysis. The carbon materials and resulting catalysts were characterized morphologically using nitrogen physisorption, coupled with non-local density functional theory (NLDFT) analysis to calculate pore size distributions. Graphiticity was assessed via X-ray Diffraction (XRD), bulk nitrogen content was observed using CHN combustion analysis and iron content by Inductively Coupled Plasma (ICP). The catalysts were characterized electrochemically using rotating ring-disk measurements. The results indicate that substrates adsorbing the most nitrogen and iron show the highest activity. Furthermore, a relationship found between mesoporosity and nitrogen adsorption indicate the importance of transport of precursors to potential active sites. (C) 2013 The Electrochemical Society. All rights reserved.