[WI2(Co)(2){P((OPr)-Pr-i)(3)}(eta (2)-EtC2Et)] crystallizes in the monoclinic space group P2(1)/n, with a = 11.101(12), b = 16.272(18), c = 14.892(17) Angstrom, beta = 93.27(1), Z = 4. The geometry can be considered to be pseudo-octahedral, with the 3-hexyne ligand occupying one site, with two iodo-groups, and the P((OPr)-Pr-i)(3) ligand completing the equational plane of ligands, with two trans-carbonyl groups occupying the axial sites.