The reaction behavior of GeO2 powder in CH4 flow was investigated at 885-1075 K. Equilibrium thermodynamic analyses revealed that GeO2 was reduced to Ge by CH4. Mass measurement, x-ray diffraction and scanning electron microscopy techniques were used to characterize the products. The reactivity between GeO2 and CH4 increased with the reaction temperature. The CH4 decomposition at 1075 K sufficed for the reduction of GeO2. Substantial mass loss was observed at 1075 K which was attributed to the oxide sublimation in the form of GeO. The residue contained only GeO2. A powdery Ge deposit was obtained from the sublimated oxide in the downstream side of the reaction tube. It was proposed that the oxide sublimation and Ge formation took place by the reactions between the oxides and the by-products of CH4 decomposition. This study may be extended to GeO2-containing scraps to produce Ge from them in CH4 flow.