Organic-inorganic composite membranes based on sulfonated poly (arylene ether ketone sulfone) (SPAEKS) and 1-ethyl-3-methyl imidazolium phosphotungstate (PWA-IL) have been prepared. PWA-IL with three imidazole cations per unit is prepared successfully through molecular modification of phosphotungstic acid with ionic liquid (IL). The obtained PWA-IL is introduced into SPAEKS matrix aiming to enhance the proton conductivity and decelerate the leakage of ionic liquid. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and scanning electron microscope (SEM) are used to characterize and confirm the interaction between PWA-IL and SPAEKS. Higher degree of sulfonation benefits both dispersion and retention of PWA-IL in the SPAEKS matrix significantly. In particular, the obtained SPAEKS-80/PWA-IL membrane shows excellent long-term stability with 98.4% of PWA-IL residue after 132 h in water due to the intensely interaction between SPAEKS and PWA-IL. It is found that PWA-IL causes a higher IEC value, resulting in higher proton conductivity compared to pristine SPAEKS membranes. Simultaneously, the PWA-IL plays a positive role in improving methanol resistance. The individual membrane SPAEKS-80/PWA-IL exhibits good proton conductivity (0.127 S cm(-1)) under fully hydrated conditions at 80 degrees C.