This paper proposes a novel two-step thermochemical cycle for hydrogen production from water using germanium oxide. The thermochemical cycle is herein referred to as KIER 4. KIER 4 consists of two reaction steps: the first is the decomposition of GeO(2) to GeO at approximately 1400-1800 degrees C, the second is hydrogen production by hydrolysis of GeO below 700 degrees C. A 2nd-law analysis was performed on the KIER 4 cycle and a maximum exergy conversion efficiency was estimated at 34.6%. Thermodynamic analysis of GeO(2) decomposition and hydrolysis of GeO confirmed the possibility of this cycle. To demonstrate the cycle, the thermal reduction of GeO(2) was performed in a TGA with mass-spectroscopy. Results suggest GeO(2) decomposition and oxygen gas evolution. To confirm the thermal decomposition of GeO(2), the effluent from GeO(2) decomposition was quenched, filtered and analyzed. SEM analysis revealed the formation of nano-sized particles. XRD analysis for the condensed-filtered particles showed the presence of Ge and GeO(2) phases. The result can be explained by thermodynamic instability of GeO. It is believed that GeO gas disproportionates to 1/2 Ge and 1/2 GeO(2) during quenching. 224 ml hydrogen gas per gram of reduced GeO(2) was produced from the hydrolysis reaction. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.