Agarose based electrolyte containing magnetic Co3O4 nanoparticles is studied for quasi solid state dye sensitized solar cells (DSSCs) under external magnetic field treatment. SEM studies reveal he existence of oriented microstructure in Co3O4 modified agarose electrolyte film under proper magnetic field intensity. The formation mechanism of this ordered structure induced by magnetic field is analyzed. The impedance analysis shows that the ionic conductivity of Co3O4 modified agarose electrolyte is obviously increased by applying magnetic field intensity of 25 mT. Improved electron recombination process and photoelectric performance are observed in DSSCs under certain magnetic field treatment by electrochemical impedance spectra (EIS) and photovoltaic studies. The DSSC treated with magnetic field can maintain the efficiency unchanged for 434 hours without sealing. This is attributed to the high ionic conductivity and improved electron transfer process in DSSC resulting from the magnetic field treatment. Comparison of photovoltaic performances for Co3O4 and NiO modified DSSCs under 25 mT magnetic field treatment shows that Co3O4-modified DSSC exhibits higher energy conversion efficiency than that of NiO-modified one at the same condition. (C) 2014 Elsevier Ltd. All rights reserved.