A series of soluble trinuclear and tetranuclear copper(I) complexes containing mu(3)-eta(1) acetylides [Cu(3)(mu-dppm)(3)(mu(3)-eta(1)-C equivalent to CR)](2+), [Cu(3)(mu-dppm)(3)(mu(3)-mu(1)-C equivalent to CR)(2)](+) and [Cu(4)(PPh(3))(4)(mu(3)-eta(1)-C equivalent to CR)(4)] have been synthesized and shown to exhibit rich photoluminescent behaviour at room temperature. The electrochemistry of the trinuclear Cu(I) acetylide: complexes and the excited- state redox properties of [Cu(3)(mu-dppm)(3)(mu(3)-eta(1)-C equivalent to CC(6)H(4)OMe-p)(2)](+) have been investigated. The X-ray crystal structures of [Cu(3)(mu-dppm)(3)(mu(3)-eta(1)-C equivalent to CC(6)H(4)OMe-p)(2)](+) and [Cu(4)(PPh(3))(4)(mu(3)-eta(1)-C equivalent to CC(6)H(4)OMe-p)(4)] have been determined.