The title compound, [Pt(C15H18NO2S)Cl], was obtained by the cyclo-metallation reaction of cis-bis-(benzonitrile) dichlorido-platinum(II) with N-benzyl-idene-l-methio-nine allyl ester in refluxing toluene. The PtII atom has a square-planar geometry and is tetra-coordinated by the Cl atom and the C, N and S atoms from the benzyl-idene methio-nine ester ligand. In the crystal structure, the S atoms show opposite chiral configurations with respect to the-carbon of the methio-nine, reducing steric repulsion between the methyl and allyl ester groups.