The stability of electrolytes based on gamma-butyrolactone was investigated by electrochemical and spectral methods during storage. It was established, the basic source of the electroactive products collecting during storage of electrolyte is irreducible water The water action is especially strongly developed at presence of lithium tetrafluoroborate, which susceptible to hydrolysis reaction. On the basis of data analysis of spectroscopic measuring it was concluded, that at presence of LiBF₄ the partially disclosing of butyrolactone rings with addition of lithium atoms to oxygen atoms with formation ether and ester groups takes place.