The authors investigate the thermal behavior of localized surface plasmon resonance (LSPR) of Au∕TiO2 core/shell nanoparticle arrays. Thermal annealing is carried out in three different routes, i.e., pre-TiO2 annealing, post-TiO2 annealing, and combinational annealing. It is found that the pre-TiO2 annealing causes a blueshift in LSPR, the combinational annealing results in a redshift, and the post-TiO2 annealing leads to an initial blueshift, followed by a redshift, and finally reverts to a blueshift. These resonance shifts correlate well with morphologic changes in Au cores and crystallization of TiO2 shells revealed by atomic force microscopy, x-ray diffraction, and x-ray photoemission spectroscopy.