Proton exchange membrane fuel cells (PEMFCs) have been identified as one of the most promising renewable energy system for use in automotive applications. However, due to the wide range of weather conditions around the world, the PEMFCs must be stable for operating under these variable conditions. One of the inefficiencies of PEMFCs in automotive applications is during vehicle warm-up, where the low hydration level within the PEMFC can lead to a low performance of the fuel cell. In this study, a proton exchange membrane (PEM) was prepared with regular, microstructured features tuned over a range of aspect ratios. These microstructured membranes were incorporated into MEAs and analyzed for their membrane, proton, and oxygen transport resistances. These fuel cells were tested under different conditions to simulate vehicle start-up, normal operating conditions, and hot operating conditions. It was determined that microstructured PEMs improved performance over planar PEMs under both the start-up and hot conditions. Despite the improved performance of the microstructured PEMs, a high hydrogen crossover and short-circuit current were also observed for these samples. Adjusting the preparation techniques and tuning the dimensions of the microstructures may provide avenues for further optimization of PEMFC performance. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.