The dinuclear copper(II) cryptate [Cu2L](ClO4)4 (1) cleaves the C−C bond of acetonitrile at room temperature to produce a cyanide bridged complex of [Cu2L(CN)](ClO4)3·2CH3CN·4H2O (2). The cleavage mechanism is presented on the basis of the results of the crystal structure of 2, electronic absorption spectra, ESI-MS spectroscopy, and GC spectra of 1, respectively