A series of new ethylenediamine (en) platinum(IV) complexes of the type Pt(IV)enX2A2 , with X2= cyclobutane-1,1-dicarboxylato (CBDCA), dichloro or bis(decanoato) and A = acetato, dodecanoato, tetradecanoato, hexadecanoato, octadecanoato, adamantanecarboxylato (Ad) or , 12α -diformoxy--cholato (DFCA) were synthesized and characterized by elemental analysis, infrared and NMR (H1andC13) spectroscopic techniques. Previous platinum(IV) compounds were usually restricted to trans-dihydroxo or trans-dichloro platinum(IV) complexes. Recently trans-dicarboxylato platinum(IV) complexes with mainly acetate, trifluoracetate or short-chain carboxylate groups (<11 carbons) in the axial position have been described in the literature[1,2,3]. In this paper we report on the synthesis and characterization of a new class of ethylenediamine platinum(IV) compounds that have high lipophilic long-chain carboxylate ligands either in the axial or equatorial position. The platinum(IV) compounds with the lipophilic trans-carboxylate ligands in the axial position were prepared by acylation of the trans-dihydroxo platinum(IV) species using an acyl halide in the presence of pyridine. In contrast to previous publications[1] the yields were excellent (up to 94%!).