The complexes of the Schiff base of racemic gossypol with 5-hydroxy-3-oxapentylamine (GSBH) with H + and monovalent metal cations were synthesized and studied ESI mass spectrometry and the PM5 semiempirical calculation. The Schiff base studied exists in chloroform solution in the enamine-enamine tautomeric form. After protonation the tautomeric form changes into the imine-imine one. The GSBH molecule form 1:1 complexes with Li + , K + and Rb + cations in which the enamine-enamine tautomeric form is favoured. The structures of the protonated Schiff base and its complex with Li + and K + cation as well as the respective hydrogen bonds within these structures are discussed.