||The effect of substituents at C2 and N3 positions of imidazolium group on properties of the PAEK based anion electrolyte membranes were studied. The membranes were applied for alkaline water electrolysis using zero gap designed cell to evaluate cell performances. All membranes exhibited better ionic conductivity and electrochemical performance than the commercial Fumasep FAA-3. The C2 methyl and N3 butyl substituted imidazolium-based membrane (PAEK-APMBI) specifically showed high ionic conductivity of 0.0154 S cm-1 and the voltage of 2.53 V at the current density of 2 A cm-2 in 10 wt% KOH at 60 °C, while those of Fumasep FAA-3 membrane were 0.013 S cm-1 and 2.63 V, respectively. Especially, the PAEK-APMBI showed the excellent alkaline stability with the 96 % IEC retention after long-term treatment in alkaline condition, while the FAA-3 showed a significant reduction in IEC to 38 %. Therefore, the PAEK-APMBI may become a potential to be applied in AEM electrolysis system.