Abstract: The hydrolysis reactions of Pen-K in water and in CTAB micelles have been studied by UV spectra. The results show that CTAB micelles can inhibit the hydrolysis, but the tendency of pH value change of the hydrolysis of Pen-K in the CTAB micelles is the same as that in water, which indicates that H＋ concentration has small effect on the inhibition. The investigations of IR and micro-polarity show that the stability of Pen-K is increased by the location of some Pen-K in the railings of the CTAB micelles.

Key words: Penicillin potossiun salt(Pen-K), CTAB, Micelles, Hydrolysis, Inhibition