Reactions of PtO+ with O-2 and CO2 and the collision-induced dissociation of PtO+ with Xe and of PtO2+ with Xe and Ar have been studied as a function of kinetic energy using guided ion beam tandem mass spectrometry in order to elucidate the thermochemistry of PtO2+. The kinetic energy dependences for these reactions show endothermic behavior except for Pt+.O2 + Xe --> PtXe --> + O-2. Analyses of the endothermic reaction cross sections yield the 0 K bond dissociation energies (BDEs) in eV (kJ/mol) of D-0(OPt+-O) = 3.06 +/- 0.07 (295 +/- 7), D-0(Pt+-O-2) = 0.67 +/- 0.05 (65 +/- 5), D-0(OPt+-CO) 2.21 +/- 0.10 (213 +/- 10), D-0(OCPt+-O) = 3.21 +/- 0.12 (310 +/- 12), and D-0(Pt+-Ar) = 0.34 +/- 0.09 (29 +/- 9), reasonably consistent with available theoretical values. Combining the OPt+-O BDE measured here with literature data also yields the ionization energy of OPtO as 10.56 +/- 0.48 eV. These data, along with complementary ab initio calculations, enable the potential energy surfaces for the activation of O-2 by Pt+ to be mapped out in some detail. Evidence is presented that PtO2+ has stable structures of both O-Pt+-O and Pt+.O2.