The multi-step thermochemical water splitting cycle based on MnFe2O4 Na2CO3 has emerged as an attractive process due to its relatively low reaction temperature. The main challenges are how to enhance its H-2/O-2 release rates and capacities. Herein, a series of MnFe2O4 with different microstructures synthesized by hydrothermal method were tested in H2O splitting reaction. It was found that MnFe2O4 samples with smaller particle size and fine crystallinity exhibited higher H-2 production which was benefit from enhanced intimate contact between homogeneous particles and better ionic transport within fine crystals. In order to enhance the reaction kinetics of the O-2 release reaction, a hydrolysis treatment was introduced to the multi-step cycle. As a result, the lamellar structure of Na+ extracted Na1-x(Mn1/3Fe2/3)O-2 oxide became unstable and collapsed into cubic MnFe2O4 spinel structure more easily under heating, a structure characteristic suitable for O-2 release reaction. Compared to direct O-2 release reaction between layered Na(Mn1/3Fe2/3)O-2 oxide and CO2, the hydrolysis treatment lead to much faster reaction rate. (C) 2016 Elsevier Ltd. All rights reserved.