Synchronous measurement of neutron imaging and EIS was conducted continuously and each image/EIS spectrum is referred to a sample with a number, such that increasing sample numbers represent the evolution of the experiment. Fig. illustrates the membrane resistance, anodic charge transfer resistance, and cathodic double-layer capacitance fitted through equivalent circuit modelling. Proton transport resistance is inversely proportional to water content before membrane saturation, leading to a continuous decrease in membrane resistance from 1.25 mΩ as overall water content increases. Consequently, up to sample 29, the two variables exhibit a linear inverse relationship. This relationship can be quantified using correlation coefficients ranging between 1 and -1, with 1 indicating perfect positive correlation, 0 representing no correlation and -1 denoting perfect negative correlation. Fig. shows the correlation coefficients between water content and membrane resistance for different sample sizes. When computed using the first 29 samples, the correlation coefficient is -0.823, reaching as low as -0.876 using 16 samples. However, membrane resistance ceases to decrease after saturation, achieving a minimum value of approximately 1 mΩ.