The study presents the various reaction steps of cisplatin hydrolysis and isomerization to transplatin. The formation of H2O-cisplation and 2H2O-cisplatin on dissociation of –Cl atoms as stable intermediates has been demonstrated. Similar study for transplatin is also carried out to compare the reaction pathway with that of cisplatin and also the relevance of this reaction mechanism for having contrasting anticancer property of these isomers. The formation of solvated cisplatin is favorable, which may produce inefficiency of DNA binding. In addition transformation of cisplatin to transplatin on dissociation of –Cl atom requires energy barrier of 22.7 kcals/mol. The work also discusses the probability of transformation from cisplatin to transplatin on dissociation of –Cl atom.