Spectroscopic results are presented concerning the 2CH excitation around 1.5 mm in van der Waals complexes of acetylene (C2H2) with Ar, Kr, N2, CO2, N2O and C2H 2. Many are reviewed from the literature, with some updates. Previously unpublished results are also presented, concerning the mechanism of formation of C2H2-Ar in the supersonic jet, the assignment of new spectral structures in C2H2-N2O, and the first observation of 2CH excitation in C2H2-Ne, C 2H2-H2O, C2H2-D 2O and (C2H2)n. Lifetimes of these 2CH vibrationally excited dimers are discussed. © 2012 Taylor and Francis. ; SCOPUS: cp.j ; info:eu-repo/semantics/published