The effect of cetylpyridinium bromide (CPB) and sodium dodecyl sulphate (SDS) on the direction and the rate of the reaction of o-dimethylaminomethylphenol (MP) with p-nitrophenyl diphenyl phosphate (1) has been studied by P-31 NMR and spectrophotometry. It was shown that the reaction of MP with 1 proceeds in two steps both with and without the surfactant. The product of transesterification is formed in the first step. The second step is hydrolysis catalyzed by the aminomethyl group yielding equal amounts of diphenyl phosphate and o-dimethylaminomethyl phenyl phosphate. The reaction of MP with 1 is catalyzed by CPB and inhibited by SDS. The ratio between the rates of the first and the second stages changes in the presence of surfactant. The parameters of the reaction of MP with 1 inhibited by micellar SDS were calculated.