Dimethylplatinum(II) complex [PtMe2(pbt)], 1, with pbt = 2(2pyridyl)benzothiazole ligand, can react with dichloromethane solvent to give the corresponding organoplatinum(IV) complex [Pt(Cl)(CH2Cl)Me2(pbt)]. The reaction gives exclusively trans addition product in which Cl and CH2Cl are located trans to each other. The suggested mechanism for this oxidative addition reaction was computationally investigated and related species during this process are proposed. DFT calculations show that the reaction proceeds through a transition state with the energy barrier of 97.5 kJ/mol. Attempts to grow crystals of the Pt(II) complex 1 in CH2Cl2/nhexane mixture of solvents forms the dichloro Pt(IV) complex [PtCl2Me2(bpt)], which its structure is determined by X-ray crystallography.