We have reported the synthesis and characterization of two new trans platinum complexes in the phosphane series, where the phosphane ligand is triphenylphosphine [P(Ph)3] and the group in the trans configuration is represented by chiral aliphatic amines, (racemic in complex 1 and S–NH2CH2CH(CH3)CH2CH3 in complex 2). The anti-proliferative activity detected in tumor cells treated with the two new complexes is more pronounced when the aliphatic amine is racemic compared to the S-enantiomer. Moreover, for both compounds, the activity is fast after cell exposure and, unlike that of cisplatin, virtually independent of the duration of cell challenge.