Open-cathode fuel cell power production increases significantly when gas diffusion media (GDM) compressive stress is increased to values greater than those recommended for forced-convection fuel cells by mitigating common shortcomings related to cell thermal and water management. Increasing GDM compression from 20% to 37% reduces cell contact resistances by an order of magnitude. This decreases ohmic resistance by 32% and increases current density by 31% at 0.6 V when GDM compression increases from 20% to 40%. Though the effect of GDM compression on contact and ohmic resistances is significant, higher compression also improves thermal management and cell hydration, which are quantified by decreasing cathode surface temperatures and lower charge transfer resistances. A disadvantage of increasing GDM compression is the onset of a rising mass transport resistance at the highest levels of GDM compression (37-40%). However, this effect is of secondary importance compared to the benefits of higher GDM compression on enhancing cell hydration and reducing ohmic resistance as higher GDM compression results in the greatest power production in all operating conditions tested. (C) 2019 The Electrochemical Society.