Abstract: The non-covalent complexes of α-, β- or γ-cyclodextrin(α-, β- or γ-CD ) with piperazine derivative compound SIPI5358 were investigated by electrospray ionization mass spectrometry(ESI-MS) and UV spectrometry. The mass spectrometry results reveal that SIPI5358(guest) and α-, β- or γ-cyclodextrin(host) can be form 1:1 complexes in solution. The results obtained from ESI-MS are further confirmed by UV spectra.