The hydrolytic decomposition of the organophosphorus ecotoxicant paraoxon in alkaline micellar solutions of a cationic surfactant with a carbamate fragment (CB-2-16) has been investigated by means of spectrophotometry. The stronger catalytic effect of micellar solutions aged during several days in comparison with freshly prepared ones has been associated with alkaline hydrolysis of the carbamate surfactant and the formation of a mixed system of CB-2-16 with its decomposition product cetyl(2-hydroxyethyl)dimethylammonium bromide (1H NMR spectroscopy data). In the absence of alkali, the decomposition products of the carbamate surfactant have not been detected for more than four months, indicating its hydrolytic stability in a neutral environment.