Cu-Mg-Al mixed oxides in basic media are shown to be efficient catalysts in the oxidative coupling of phenylethyne to 1,4-diphenylbuta-1,3-diyne. Catalysts containing 33 at.% of Cu(II), related to the total metal content, with different ratios of Mg(II) and Al(III) were prepared by precipitation of metal nitrates with sodium carbonate and calcined at different temperatures. The samples were characterized by means of XRD, TEM, TG-MS, XPS, N2O titration, and N-2 physisorption. The catalytic behavior was tested in n-butanol (0-0.1 M NaOH) in an autoclave under oxygen atmosphere (0.5-4 MPa) at different temperatures (303-353 K). Highest yields of 1,4-diphenylbuta-1,3-diyne (84%) were obtained with catalysts based on Cu-Mg-Al lamellar double hydroxides (LDHs). Typical selectivities to 1,4-diphenylbuta-1,3-diyne were in the range of 85-92%, depending on reaction conditions and conversion. Cu(II) on the catalyst surface was found to be crucial as a redox site in the coupling of phenylethyne. However, the mere presence of Cu(II) on the surface is not sufficient for a highly active catalyst. Cu(II) must be embedded into a specific matrix in order to exhibit high catalytic activity. The hydrotalcite-like phase (LDH)in Cu-Mg-Al catalysts provides such a matrix.