Water splitting for the production of oxygen is a promising strategy to advance many renewable energy conversion systems, while the cost-effective and green synthesis of a high-performance catalyst composed of earth-abundant elements is still a big challenge. A facile and green synthesis of nonprecious MnFe2O4 nanorod arrays at low temperature is developed here, where the as-obtained hierarchical MnFe2O4 nanorod arrays exhibit mesoporous structure, large surface area and nice dispersion. These fabricated mesoporous MnFe2O4 nanorod arrays are efficient for water oxidation in 0.1 M NaOH, giving rise to a low overpotential of similar to 0.31S V-RHE at 10.0 mA cm(-2), a high current density (10 times higher than that of commercial 20 wt % Pt/C catalyst at 1.80 V-RHE) and largely enhanced stability. These performances are much superior to previously reported electro-oxidation catalysts as well as the state-of-the-art RuO2 and precious 20 wt % Pt/C catalysts. In particular, this preparation method of MnFe2O4 nanorods is amenable to fast and cost-effective production and shows promising applications in water splitting and other clean energy systems.