Gold nanoparticles (Au NPs) were loaded on rutile (R)- and anatase (A)-TiO2 with the mean size varied and the loading amount maintained constant by the heating temperature-varied deposition precipitation technique. Loading Au NPs on R-TiO2 (Au/R-TiO2) dramatically enhances the plasmonic photocatalytic activity for the decomposition of 2-naphthol under visible-light irradiation (lambda(ex) > 430 nm), whereas the activity of Au/A-TiO2 remains a low level. Also, the photocatalytic activity of Au/R-TiO2 drastically increases with decreasing mean Au particle size or increasing Au surface area in spite that the localized surface plasmon resonance (LSPR) significantly weakens. These results are comprehensively rationalized in terms of the adsorption property of the photocatalysts for 2-naphthol. Further, mesoporous films consisting of Au/TiO2 particles were formed on fluorine-doped tin oxide electrode (Au/R-TiO2/FTO). The action spectra of the initial rate of the potential shift for a three-electrode photoelectrochemical cell using Au/TiO2/FTO as the working electrode indicates that this reaction proceeds via the LSPR-induced hot-electron transfer mechanism. (C) 2018 Elsevier Inc. All rights reserved.