A new technique for the back-extraction using photoreduction by the fourth harmonic of Nd:YAG laser has been successfully demonstrated in a liquid-liquid extraction system composed of a 1-octanol solution of Eu3+(TODGA)(n) complex and water. The reduced product, Eu2+ ion, was stabilized by addition of 15-crown-5. The back-extraction process was investigated by laser-induced fluorescence spectroscopy. The results indicated slow diffusion of Eu2+(15-crown-5)(m) in the organic phase and fast transfer through the interface to the water.