Сobalt-based catalysts are one of the possible candidates for catalysts that accelerate the decomposition of water to produce energy. In this work, the one-dimension GeCo nanostructures have been prepared by electrochemical deposition in a three-electrode cell. The samples have been annealed in atmosphere at various temperature (300 ºC, 450 ºC, 600 ºC). Effect of thermal annealing on the composition of Ge-Co nanostructure has been studied. The morphology of the obtained Ge-Co nanostructures has been investigated using scanning electron microscopy The method of X-ray diffraction analysis has been used to investigate composition changes of Ge-Co. Diffractograms show the presence of Co2GeO4 catalyst at an annealing temperature of 600 ºC. The sample with this annealing temperature shows the best properties as oxygen evolution catalyst.