By reaction of [NBu(4)](2)[Pt-2(mu-C6F5)(2)(C6F5)(4)] with 1,8-naphthyridine (napy), [NBu(4)][Pt(C6F5)(3)(napy)] (1) is obtained. This compound reacts with cis-[Pt(C6F5)(2)(THF)(2)] to give the dinuclear derivative [NBu(4)][Pt-2(mu-napy)(mu-C6F5)(C6F5)(4)] (2). The reaction of several HX species with 2 results in the substitution of the bridging C6F5 by other ligands (X) such as OH (3), Cl (4), Br (5), I(6), and SPh (7), maintaining in all cases the naphthyridine bridging ligand. The structure of 3 was determined by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system, space group P2(1)/n, with a = 12.022(2) Angstrom b = 16.677(3) Angstrom, c = 27.154(5) Angstrom, beta = 98.58(3)degrees, V = 5383.2(16) Angstrom(3), and Z = 4. The structure was refined to residuals of R = 0.0488 and R(w) = 0.0547. The complex, consists of two square-planar platinum(II) fragments sharing a naphthyridine and OH bridging ligands, which are in cis positions. The short Pt-Pt distance [3.008(1) Angstrom] seems to be a consequence of the bridging ligands.