Metal complexes containing sulfur are expected to have conductive property because of S••.S interaction. Wudl et al. reported Fe(III), Ni(II), Co(II) and Cu(II) complexes with 5-tetrathiobenzene.1 They showed that these complexes have high conductivity and magnetic property. But the crystal structure has not been reported. In this study we have characterized dinuclear copper(I) complex with 1,2,4,5-tetramethylmercaptobenzene crystallographically. Yellow single crystals of [Cu(tmmb)I]2 (tmmb= 1,2,4,5-tetramethylmercaptobenzene) (1) were obtained from a mixture of CuI (5.7 mg, 30 mmol/1) and tmmb (5.2 mg, 20 mmol/1) in acetonitrile under purified argon after 3 d. The tmmb was synthesized from 1,2,4,5tetrafluorobenzene and sodium thiomethoxide in dry 1,3-dimethyl-2-imidazolidinone.2 X-Ray data collection was performed on a Rigaku AFC-7R diffractometer under the conditions given in Table 1. The structure was solved by a direct method and an empirical, spherical and absorption correction was performed using a