Stochastic modeling of GDL structures requires a detailed characterization of the constituent elements of the material. In this work, a variety of imaging methods, including optical microscopy, microscale computed tomography, and scanning electron microscopy were used to characterize seven commercially available gas diffusion layers (GDLs). The result is a catalogue of the following geometrical characteristics: fiber diameter, fiber pitch and co- alignment, areal weight and volume, and microporous layer (MPL) crack size and frequency. This catalogue, when combined with previous GDL characterizations, is expected to provide enough information to create representative, predictive, stochastic models of the GDL. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.