The nitrile complex trans-[PtCl 4 (EtCN) 2 ] reacts with the aldoximes HON C(H)R [R=C(Ph)( O), Me, Ph] in CH 2 Cl 2 to afford products of the addition of the aldoxime HON group across the nitrile CN triple bond, i.e. trans-[PtCl 4 {NH C(Et)ON C(H)R} 2 ] (1-3). These compounds were characterized by elemental analyses, FAB MS, IR and 1 H and 1 3 C{ 1 H} spectroscopies and X-ray structure determination has been performed for 1. In CHCl 3 solution, 1-3 undergo the spontaneous imine ligand splitting to achieve the carboxamide complex trans-[PtCl 4 {NH C(Et)OH} 2 ] and RCN thus giving the first example of a ligand-mediated dehydration of aldoximes. The carboxamide and RCN products are also formed upon treatment of trans-[PtCl 4 (EtCN) 2 ] with 2 equiv. of HON C(H)R in CH 2 Cl 2 .