This study examines the effect of various quaternary ammonium groups on AEMWE performance and hydrogen crossover in blends of quaternized polystyrenes with O-PBI. Due to their higher hydroxide conductivity (69 mS cm-1 at 80 °C, 90% RH), trimethylammonium groups enable AEMWE to reach 1.0 A cm-2 at 2.0 V. The trimethylammonium groups exhibit low hydrogen crossover, ranging from 1.5% to 0.3%, across current densities of 50 to 1000 mA cm-2. Low hydrogen crossover is essential for AEMWE in terms of safety and efficiency.