Résumé : Square planar metallic and homonuclear bimetallic complexes of Pd(II) with 2-thiouracil (HTU) and organophosphines have been synthesized and characterized by FT-IR and multinuclear 1H, 13C, 31P NMR spectroscopy. The thiouracil ligand TU acts as bidentate, is bound through the thioxo moiety and the endo amino group and forms a bridge between a PdCl(R3P) and a PdCl(R3P)2 moiety [R3P = Ph3P (o-tolyl)3P, ClPh2P] in the homonuclear bimetallic complexes. The square planar geometry around Pd(II) has been confirmed for these complexes by a single-crystal X-ray diffraction study of compound 1, [Pd2(TU)(PPh3)3Cl2]. These compounds were also screened against human tumor cell lines and showed promising in vitro cytotoxicity. Copyright © 2007 John Wiley & Sons, Ltd.