Infrared predissociation spectroscopic studies of systematically solvated acetylene clusters, (C₂H₂)_n⁺ n = 1 – 4, reveal the structural evolution of these cations with increasing cluster size. The argon predissociation spectrum of the acetylene dimer coupled with harmonic frequency calculations suggests the dominant species adopts a cyclobutadiene-like geometry. The argon solvated trimer, C₆H₆⁺ · Ar, predominantly loses C₂H₂ · Ar suggesting that the trimer is composed of a covalently bonded “dimer core”, which exhibits a spectrum different than cyclobutadiene, and is solvated by a weakly bound acetylene. The same spectral features are retained in the tetramer suggesting that the dimer core survives the solvation of additional acetylene molecules. The minor loss channel of C₆H₆⁺ · Ar, loss of a single Ar, shows multiple features believed to be from a number of covalently bonded C₆H₆⁺ species.