Li(+)/H(+) exchange was performed on Li5La3Nb2O12 using CH3COOH. After X-ray powder diffraction experiments to check the quality of Li5-xHxLa3Nb2O12, the chemical formulation was determined by thermogravimetric analysis coupled with mass spectrometry and flame photometry. The results showed unambiguously that the Li(+)/H(+) exchange was not total and that some CH3COOH remained in the sample. Raman experiments revealed in addition that the organic contribution on the spectrum was due either to metal acetate or to ionic bond to the crystal.