The micellar catalysed reactions between hydroxide or hydroperoxide anion and mono phosphate ester of 4-CMPP has been examined in buffered medium (at pH 8.0-10.0) with borate ions. First order rate constant (Kψ) for the reaction of OH− with 4-CMPP go through maxima increasing with the concentration of cetyl trimethyl ammonium bromide (CTABr). The micelles of CTABr are very effective catalysts to the reactions of phosphate mono ester. Rate enhancement depends upon the hydrophobicity of the nucleophile for the reactions of mono phosphate ester. Rate constants measured with HO2 − ions are approximate.