Recent attempts to use localized surface plasmon resonance (LSPR) for photoexcitation of molecules suggests the possibility to modify the excitation processes and the selection rule of electrons [1, 2]. Among several choices of the applications of LSPR, the system of Au-nanostructured titanium dioxide (TiO2) is one of promising approaches for plasmon-enhanced photoenergy conversion under illumination of visible and near infrared light . It has been suggested that photo-induced electron injection from the Au structure into the TiO2 conduction band occurs by localized surface plasmons excitation. In this system, Au-nanostructured TiO2 enabled efficient water oxidation owing to the excitation of multiple electrons and holes generated by near-infrared light, and the evolution of O2 via four-electron oxidation of water. In this work, size-controlled Au-nanostructures was fabricated on a TiO2 single crystalline by means of angle-resolved nanosphere lithography (AR-NSL) to measure surface-enhanced Raman scattering (SERS) from the intermediate species at water oxidation process at the electrode-electrolyte interface under near-infrared light irradiation. SERS spectra were obtained from the size-controlled Au nano-dimer (Au-NSL) arrays on a single crystalline TiO2 immersed in 0.1 M NaF solution. For comparison, we also measured SERS spectra from Au-NSL on indium tin oxide (ITO). Observed spectral feature at ~580 cm-1 can be attributed to Au-O stretching vibrations of adsorbates. This wavenumber suggests that adsorbed hydroxide anion with Au-O bonding are produced as intermediate of water oxidation reaction at Au/TiO2. It should be noteworthy that Au-O vibration was observed at more negative potential on Au/TiO2 than that of Au/ITO. Negative shift is attributed to the water oxidation on Au/TiO2 is assisted by electrons and holes generated by plasmon-induced excitation.