Hydrolysis of mono-2-methoxy-phenyl phosphoramide (mono-2-MPPA) was studied in micellar solutions of cetyl trimethyl ammonium bromide (CTABr) at pH 9.0. The hydrolysis was carried out by first order kinetics with respect to mono-2-MPPA concentration. At the concentration of critical micelle concentration (CMC), the rate of hydrolysis was increased with increasing the CTABr concentration. The binding constant of micelle for mono-2-MPPA and the rate constant in micellar pseudo phase were determined from kinetic data using the pseudo phase model.