C-H bond cleavage and formation is one of the most essential elementary reactions in organic chemistry. Herein, a heterolytic sp(3) C-H bond reductive elimination from hydroxyCp dimethylplatinum(IV) B is reported. Protonation of cyclopentadienone dimethylplatinum(II) A afforded B via the protonation of the ligand. Successive C-H bond formation from the C anion of the methyl group and the H cation of the hydroxyCp group was observed in the presence of carboxylic acids or hydrogen chloride. The reaction was accompanied by the concurrent reduction of Pt(IV) to Pt(II). Experimental and theoretical investigations suggested that the mechanism for the C-H bond formation was acid-mediated metal-ligand cooperative outer-sphere reductive elimination.