Microporous layers (MPLs) of gas diffusion layers (GDLs) were modified by multiwall carbon nanotubes (MWCNTs) using a wet-chemical approach. Carbon nanotubes were dispersed along with other MPL components and coated onto a GDL backing. The electronic resistance of the GDL was significantly reduced by the addition of MWCNTs. A larger mean pore diameter was obtained as compared to the reference substrates. The improved performance of proton exchange membrane fuel cells (PEMFCs) using such CNT-doped GDLs is attributed to a lower electronic resistance along with improved mass transport. Synergy effects of different carbon materials with MWCNTs and advanced dispersion processes were found to play a key role in achieving the performance improvements. (C) 2012 Elsevier B.V. All rights reserved.