With the extraction of microstructural features and extensive characterisation with various spatial descriptors, we shift our focus onto quantifying electrode descriptors which directly influence mass diffusion, proton and electron transport across CLs. Table . displays the surface area and three-phase lengths of the microstructures as a function of their solvent composition. A clear trend can be observed with increasing IPA content in the dispersion medium, with an overall increase in the surface area of each of the respective components (pore, ionomer and carbon). However, a simple increase in pore surface area does not attest to improved electrochemical performance of the electrodes. Herein, the latter property becomes a suitable metric. Due to the nature of electrochemical reactions that take place at the CL, electrochemically active centers must be proton and electron conductive while also being accessible to the pore in order for (reactants and water) mass transport to occur. The electrochemical centers that satisfy this criterion are assumed to be points, called the three-phase boundary. Summing over the threephase boundaries over the entire electrode microstructure gives us the three-phase lengtha metric of how probable electrochemical reactions are in a given electrode. Interestingly, we also observe an increase in the three-phase length for microstructures with increasing IPA content in the solvent.