Novel and surprising biological properties were disclosed for the platinum(II) complex cis-diiodidodiisopropylamineplatinum(II). Remarkably this new platinum(II) complex manifests pronounced antiproliferative properties in vitro, in some cases superior to those of cisplatin. A peculiar reactivity with the model protein cytochrome c was indeed highlighted based on the loss of amine ligands and retention of iodides.