Abstract A high proton conductivity with low oxygen diffusivity novel composite membrane consisting 15 wt. % zeolite 4A incorporated in 2:1 blend ratio of sulfonated polyethersulfone (SPES) and polyvinylidene fluoride (PVDF) has been synthesized for energy generation through a microbial fuel cell (MFC). The prepared membrane was found to have desired functional groups, with semi-crystalline nature, high thermal stability (490 °C), and uniform morphology. The inclusion of zeolite 4A in SPES/PVDF blend induces a high-water sorption capacity (30 %), proton conductivity (0.141 Scm−1), and ion exchange capacity (1.51 meq g−1) in the composite membrane. A maximum power density of 208 ± 5 mWm-2with high COD (14,000 mg L−1) removal efficiency of 82.1 % along with low oxygen diffusivity of 7.21 × 10-8 cm2s−1 was obtained. Moreover, the impact of different cations (Na+, Ca2+, and K+) on oxygen and hydronium ion (H3O+) diffusivity on the composite membrane is investigated using the COMPASS forcefield molecular dynamic (MD) simulations. The results showed that the K+ cation has low oxygen diffusivity (4.50 × 10-8 m2s−1) with high H3O+ diffusivity (1.5 × 10-10 m2s−1) as compared to Na+ and Ca2+due to their higher cationic radius with lower electrostatic interactions. This result implies that potassium containing compound is more beneficial for the preparation of MFC solution, as K+ cation shows the desired behavior required for MFC.