We have investigated the structure of Pt(A)/MgO and PtMo6/MgO catalysts which were prepared from Pt(C5H7O2)(2) and [PtMo6O24](8-) followed by calcination, respectively, and their catalytic activities for the propane + O-2 reaction. The Pt(A)/MgO and PtMo6/MgO catalysts with atomically dispersed Pt ions were found to be as active as metallic Pt particles supported on MgO for propane combustion. A distorted spinel-like structure around Pt ion embedded at the MgO surface was proposed for the active Pt species by means of EXAFS. The atomically dispersed Pt structure was reduced with propane at 623 K to form Pt-6 clusters with Pt-O bonding to the MgO support. The Pt cluster chemically attached to the MgO surface was selective for the propane dehydrogenation. Restructuring of the Pt clusters to the atomically dispersed Pt structure was observed by oxidation with O-2 at 623 K.