We studied the methanol adsorption behavior of Pt nanoparticles that were vacuum-deposited on a TiO2(110) surface at room temperature by using an ultrahigh vacuum (UHV) scanning tunneling microscope (STM). A large number of bright spots were observed on fivefold-coordinated Ti (Ti-5c) rows of the TiO2(110) surface after exposure of the Pt/TiO2(110) to methanol vapor. We assigned the bright spots to methoxy species. These were mobile and were found to hop along the Ti-5c rows. In situ time-resolved STM observations of the formation and migration of the bright spots on the Pt/TiO2(110) were carried out in the presence of methanol. The bright spots were produced at the periphery of the Pt nanoparticles and migrated to the substrate Ti-5c rows. We discuss the spillover process and behavior of the methoxy species on the Pt/TiO2(110).