This manuscript represents a second part to the investigation of multiblock disulfonated poly(arylene ether sulfone) and poly(arylene ether nitrile) copolymers. In Part 1 it was shown that the multiblock copolymers had high ion exchange capacities (IECs), phase separation, strong membrane integrity and moderate water uptake. In this second part, the electrochemical properties of the membranes are presented and compared against those of the perfluorosulfonated Nafion 212 membrane. The disulfonated poly(arylene ether sulfone) and poly(arylene ether nitrile) multiblock copolymer membranes were fabricated into membrane electrode assemblies (MEAs), and tested in four different humidity environments at the electrodes (95/95%, 100/50%, 50/50%, and 75/25%). The hydrocarbon MEA had similar performance to the Nafion (R) 212 MEA at low current density, and outperformed the Nafion MEA at high current density for high humidities, and at lower humidities had almost comparable performance to the perfluorosulfonated MEA. The cell testing of the MEAs agreed well with the relative humidity conductivity results obtained for the membranes. (C) 2017 Published by Elsevier Ltd.