The effect of stacking multiple microbial fuel cells for stable power output was evaluated in continuous mode operation. Three single chambered air cathode CMFCs with Nafion (CMFCN), Terry cotton (CMFCT) as membranes and one without membrane (CMFCML) were operated in continuous mode. Maximum power density (PD) and COD removal efficiency was obtained for CMFCN (0.1 W/m(2), 50%) followed by CMFCML (0.062 W/m(2), 47%) and CMFCT (0.025 W/m(2), 39%) and were stable throughout the operation. To increase the power output further, stacking of CMFCs was carried in series/parallel circuitry, which yielded high power density in parallel (2.0 W/m(2); 7.2 W/m(3)) and high voltage in series (1.1 V). Study also evidenced that stacking resulted in high and stable bioelectricity by minimizing the electron losses in comparison to individual CMFCs operation. Stable and high power output signifies the impact of continuous mode operation that constantlty replenishes the substrate.