The collision induced dissociation and electron induced dissociation spectra of the [2M + H]+ and [2M + Na]+ clusters of the zwitterionic amino acid, betaine (M), have been examined in a hybrid linear ion trap Fourier transform ion cyclotron resonance mass spectrometer. Intercluster reactions are observed in the collision induced dissociation spectra of [2M + H]+ and [2M + Na]+ and in the electron induced dissociation spectrum of [2M + H]+.