The ion–molecule reactions of dimethyl ether with cyclometalated [Pt(bipy−H)]+ were investigated in gas‐phase experiments, complemented by DFT methods, and compared with the previously reported ion–molecule reactions with its sulfur analogue. The initial step corresponds in both cases to a platinum‐mediated transfer of a hydrogen atom from the ether to the (bipy−H) ligand, and three‐membered oxygen‐ and sulfur‐containing metallacycles serve as key intermediates. Oxidative CC bond coupling (“dehydrosulfurization”), which dominates the gas‐phase ion chemistry of the [Pt(bipy−H)]+ ion with dimethyl sulfide, is practically absent for dimethyl ether. The competition in the formation of C2H4 and CH2X (X=O, S) in the reactions of [Pt(bipy−H)]+ with (CH3)2X (X=O, S) as well as the extensive H/D exchange observed in the [Pt(bipy−H)]+/(CH3)2O system are explained in terms of the corresponding potential‐energy surfaces.