School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur-492 010, India Manuscript received 31 December 1997, revised 30 June 1998, accepted 20 July 1998 Kinetics and mechanism of the alkaline hydrolysis of N-p-tolylbenzohydroxarnic acid (p-X-C6H4(C=O)N(OH)C6H4-CH3 X = H, CH3, Cl) and its para-substituted methyl and chloro derivatives have been studied in 10% (v/v) aqueous dioxane at 65��. Two cases of hydrolysis applicable to two different ranges of NaOH concentrations are recognized. The relative reactivity, temperature, salt, solvent and solvent isotope effects have also been examined.