The carbon-bearing magnetite (CBM) was prepared by the carbon-deposition on the H2- treated magnetite with CO2 at 300 °C. The CBM reacted with H2O and evolved H2 gas at 300- 350 °C. The surface of the CBM was composed of a new iron(II)oxide / carbon layer (CIOlayer). X-ray diffractometry and chemical analysis showed that the CIOlayer was transformed to an amorphous carbide phase by allowing to stand in Ar stream at 300 °C, which is so reactive as to decompose H2O into H2. The mole ratio of the evolved H2 gas to the evolved CO2 was nearly equal to that in the carbide (Fe3C) decomposition reaction with H2O. During the H2O decomposition, oxygen ions are transferred to the surface layer forming iron oxide. When the carbon-bearing Ni(II)-ferrite (CBNF) was used as the solid phase, the hydrogen evolution reaction takes place without decreasing in the carbon content in the CBNF, and the evolved H2 volume was approximately 8 times higher than that evaluated from the oxidized amount of the iron ions in the CBNF. This result suggests that some amount of oxygen in the CBNF is released while allowing to stand the sample in Ar stream at 300 °C. These H2 evolution reactions can proceed at low temperature of around 300 °C. This will provide us the way to establish a unique chemical heat pump system, where the waste heat around 300 °C be transferred to chemical energy of H2. The surface layer composed of iron(II) oxide/carbon is the key compound for this reaction.