Water management is one of the major issues hindering the employment of Polymer Electrolyte Membrane Fuel Cells on a large scale. Microporous layers are fundamental for water removal from the cathode, oxygen mass transfer and electrolyte hydration. In this paper, we have employed multiple carbon phases in the MPL composition to identify possible strategies for cell performance improvement at critical conditions such as high temperature and low relative humidity. In particular, we have employed a series of graphene-based particles, in addition to conventional carbon black, because of their excellent electrical and thermal conductivities. Moreover, mixed compositions have been tested to assess possible synergic effects between the two phases. We have determined which properties are responsible for performance improvements at 80 degrees C and relative humidity of 60% and how MPLs morphological and microstructural features could be tuned in order to increase mass transfer while preserving the electrolyte membrane hydration. Promising results have been obtained and specific morphological properties of graphene nanoplatelets have been identified for a possible optimization of the MPL, however the samples produced are still at an early-stage development and further improvements are needed. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.