Microbial fuel cell (MFC) technology has been widely experimented nowadays, as it is a promising clean energy technology, which can harvest bioelectricity while simultaneously treating wastewater. Platinum (Pt), a precious transition metal, has long been regarded as a superior catalyst material for oxygen reduction reaction (ORR) at the cathode of the MFCs, however the high cost associated with it clutch it back for field scale applications. In this study, Co3O4 or Fe3O4 was blended with synthetically prepared conductive ink to act as microporous layer to explore its efficacy as an ORR catalyst. Applicability of these catalysts on cathode was investigated in dual chambered aqueous cathode MFCs and the performance was compared with MFC without any cathode catalyst, MFC with only conductive ink and another MFC with Pt as benchmark ORR catalyst. X-Ray diffraction, Fourier transform infrared spectra, Raman and field emission scanning electron microscope analysis were done to characterize the prepared catalysts. Cathode containing Co3O4 with conductive ink demonstrated higher reduction current (-30 mA) than cathode having Pt and conductive ink with Fe3O4 (-9mA each) during cyclic voltammetry analysis. MFCs having cathodes printed with conductive ink containing Co3O4 and Fe3O4 exhibited a maximum volumetric power density of 6.62Wm(-3) and 5.06Wm(-3), respectively, which were much higher than the one without any catalyst (2.95Wm(-3)). Similarly, coulombic efficiency (CE) of 22.3%, 17.1% and 11.2% was observed in MFCs having cathode with conductive ink containing Co3O4 or Fe3O4 and without any catalysts, respectively. Moreover, more than 90% chemical oxygen demand removal efficiency was observed for MFCs having cathode with conductive ink containing CCo3O4 or Fe3O4. Importantly, the performance obtained from MFC with conductive ink blended Co3O4 was found superior compared to MFC having Pt as cathode catalyst, where later produced power density of 6.13Wm(-3) and CE of 21.1%. Hence, it can be concluded that Co3O4 can be used as an alternative to expensive platinum for efficient ORR in MFCs to make this technology effective for field scale application. (C) 2019 Elsevier Ltd. All rights reserved.