This is significant insofar as most commercial alkaline electrolysers operate in the latter current density range, which provides the best compromise of capital costs (capex) and operating costs (opex) for alkaline electrolysis. If comparisons are to be made of the capillaryfed cell with commercial alkaline electrolysers at current densities in this range, then the key opportunity for further performance improvements in the capillary-fed cell lies in minimizing bubble formation at the cathode.