The electrolyte distribution inside the porous electrodes of vanadium redox flow batteries is critical to the performance, as it determines the electrochemically active surface area. Herein, the influence of thermal activation, compression, and the injected electrolyte species on the pressure drop and the wetting is investigated by means of synchrotron X-ray radiation. The saturation versus the through-plane position is quantitatively displayed as a function of time to resolve the wetting process. The initial state after the imbibition is then quantitatively compared to the saturation after flow-through conditions. It was concluded that thermal activation plays a major role in the wetting, resulting in an up to six times higher saturation. Only a minor increase in saturation between the initial wetting state and after flow-through was observed. Additionally, there are only minor differences in the wetting behavior between the vanadium species in the electrolyte, the V(III) electrolyte shows the highest saturation. Increasing compression leads to a higher pressure drop and the saturation decreases only at compression ratios higher than 50%. Air pocket formation inside the liquid column was observed and the displacement and re-emergence of air pockets after flow-through is displayed.