The effect of vacuum annealing (600 °C, 30 min) on the temperature stability against oxidation in air of germanium nanowires obtained by cathodic deposition from aqueous solutions of germanium oxide was studied by the method of photoluminescence in the visible range and Raman scattering. The stability was checked by laser annealing at temperatures above 1000 °C. It was shown that the evolution of photoluminescence and Raman peaks is associated with the formation of germanium oxide or suboxide upon laser annealing. Preliminary vacuum annealing of the sample significantly suppresses this process. The observed effect is associated with the formation of germanium oxide and the influence of indium atoms on this process.