Fuel cell technologies suffer from key cost, efficiency and degradation issues that must be resolved before they can reach their full commercial potential. Unfortunately many of the limitations of current polymer electrolyte membrane fuel cell (PEMFC) technologies are introduced, or exacerbated, by the current design of their membrane electrode assemblies (MEAs). Homogeneously constructed MEAs (i.e. the industrially standard) suffer from heterogeneity in the distribution of current, pressure, reactant concentration, water distribution and temperature, leading to numerous unintended gradients across the fuel cell which act to heterogeneously utilise, and therefore degrade, catalysts, their supports and ion conducting membranes. In HETEROMEA, we will characterise and understand the impact of intrinsic heterogeneity on MEA performance and durability. This understanding will be used to inform the design and implementation of material heterogeneously within next-generation MEAs, to 'smooth out' inefficient gradients and produce a homogeneous distribution of current, water, reactant partial pressure in operational PEMFCs; i.e. we will produce MEAs where the constituents (including e.g. Pt, ionomer, porosity, membrane) are intelligently distributed inhomogeneously, mitigating performance and durability losses. This will be enabled via the utilisation of robotic ultrasonic spray printing, a tool that allows flexible but precise control over material loading and distribution. HETEROMEA will therefore deliver a significant improvement in catalyst utilisation, mass transport resistance, charge transfer resistance and flooding, while using a standard range of industry-relevant fuel cell materials (e.g. commercial catalysts).