The rate constants of the hydrolysis of cinnamanilide derivatives were determined UV spectrometry in $H_2SO_4;(5{sim}20N)$, NaOH($5{sim}11N);at;50{sim}110^{circ}C$ and rate equation could be applied over a strong acid and strong base were obtained. Final product of the hydrolysis was a cinnamic acid. The ${ ho}$ values obtained from the slope of linear plots of log $k_{abs}$ vs. Hammet $t{sigma}$ constants were slightly negatives, Substituents on cinnamanilide showed a relatively small effect, with hydrolysis facilitated be electron donating group. Activation energy(Ea)was also calculated for the hydrolysis of the cinnamanilide. From this reaction rate equation, substituent effect and experimental of rate constants, that the hydrolysis of cinnamanillde was Initiated by the netural molecule of $H_2O$ which do not dissociate at strong acid, and proceeded by hydroxide ion at strong base.