Abstract: Negatively charged oxygen atoms can be generated by the steps of (A) supplying oxygen to a surface of a solid electrolyte, at which the surface is provided an electrode A', while supplying electric current to the electrode A', to thereby form oxygen ions; (B) causing the oxygen ions formed in step (A) to be transmitted through the solid electrolyte; (C) forming negatively charged oxygen atoms at a surface of the solid electrolyte, an opposite surface on which the electrode A' is provided, by providing electric current to an electrode A on the opposite surface, to thereby produce negatively charged oxygen atoms from the oxygen ions; and (D) applying voltage to an electrode B spaced from the electrode A, in an amount sufficient to generate an electric potential between the electrode A and the electrode B, thereby causing the negatively charged oxygen atoms to move in the direction of the electrode B. The apparatus of the present invention can be used for the above method.