Abstract Reactions of sodium benzylselenolate with several palladium(II) and platinum(II) complexes were carried out and a variety of products isolated and characterized. Reactions of Na 2PdCl 4 or K 2PtCl 4 with NaSeBz gave [M(SeBz) 2] n (M=Pd or Pt; Bz=CH 2Ph) which when treated with tertiary phosphines yielded [M(SeBz) 2(L-L)]. The latter can also be prepared by the reaction of MCl 2(L-L) (L-L=dppm, dppe or 2PPh 3) with NaSeBz. Treatment of [M 2X 2(μ-Cl) 2(PR 3) 2] with NaSeBz in 1:2 molar ratio afforded complexes of the type [M 2X 2(μ-SeBz) 2(PR 3) 2] (M=Pd or Pt; X=Cl or Me; PR 3=PEt 3, PPr n 3, PBu n 3, PMe 2Ph, PMePh 2 or PPh 3) which existed predominantly as a cis isomer. Reaction of [M 2Cl 2(μ-Cl) 2(PR 3) 2] with [M 2Cl 2(μ-SeBz) 2(PR 3) 2] gave heterobridged complexes [M 2Cl 2(μ-Cl)(μ-SeBz)(PR 3) 2], the bridging chloride in the latter can be substituted with SBu t or pz. All the complexes were characterized by elemental analysis and NMR ( 1H, 31P, 77Se, 195Pt) spectral data. Stereochemistry of these complexes has been discussed on the basis of NMR data. The crystal structure of [Pt 2Cl 2(μ-SeBz) 2(PPr n 3) 2] has established a cis configuration with a bent four-membered Pt 2Se 2 ring. The complex [Pd(SeBz) 2] n on thermolysis at 630°C yields Pd 17Se 15.