To develop cutting-edge catalysts with excellent catalytic performance, novel synthetic techniques are required. In particular, hollow oxide nanoparticles are attracting much attention as advantageous nanoreactors in which the interior cavity can be selectively functionalized with catalytically active metal nanoparticles and various oxide supports. In this report, we demonstrate that the metal/oxide interface inside a hollow nanoparticle can be changed from (Mn3O4/Pt NPs)@h-SiO2 to [Mn3O4(0.5)/CeO2(0.5)/Pt NPs]@h-SiO2 via the galvanic replacement reaction, leading to improved catalytic activity and selectivity. The change in selective methanol oxidation is determined by the CO oxidation and OH formation reactions at the metal/oxide interface. This work implies that modification of the metal/oxide interface in a hollow oxide nanosphere is an effective way to improve catalytic performance for a desired product in heterogeneous catalysis. [GRAPHICS] .