A study of the reaction of PtMe2(bipy) with IPh(C CSiMe3)(OTf) at low temperature in acetone, leading to detection of the Pt-Pt-bonded cation [Pt2Me4(C CSiMe3)(bipy)(2)](+), an intermediate in the oxidation of Pt-II to Pt-IV, is reported. The cation is assessed as Pt-III-Pt-III <-> Pt-IV-Pt-II, and at the other extreme may be regarded as a cationic alkynylplatinum(IV) center, "[(PtMe2)-Me-IV(C CSiMe3)(bipy)](+)", stabilized by "(PtMe2)-Me-II(bipy)" as a donor ligand. The detection and isolation of the [Pt2Me4(C CSiMe3)(bipy)(2)](+) cation provides a number of insights into the mechanisms of oxidation reactions.