Characterization and catalytic performance of modified Pt on SbOx for the selective oxidation of i-C4H10 and i-C4H8 to methacrolein are summarized and reconsidered in this paper. XRD revealed that the main oxide phase in Pt/SbOx catalysts under the reaction conditions was Sb6O13, while Raman spectroscopy also indicated the presence of small alpha-Sb2O3 crystallites (senarmontite), forming on or around Pt particles, with small highly dispersed O = SbOy decorating the Pt surface. These species were responsible for breaking up large Pt ensembles and suppressing the total oxidation reaction. Synergistic combination of the modified Pt and the defect pyrochlore-type Sb6O13 was essential for the selective oxidation of i-C4H10.