The rate of aqueous cleavage of N-(2’-hydroxyphenyl)phthalimide (A), monitored at 320 nm, 1.0 10–3 M NaOH, 35ºC and within CH3CN content range 1% – 80% v/v in mixed aqueous solvents, follows the reaction scheme: A + HO-/H2O ➝ B + HO-/H2O ➝ P1 + P2 where B, P1 and P2 represent N-(2’-hydroxyphenyl)phthalamic acid, phthalic acid and 2-hydroxyaniline, respectively. The values of k1 and k2 at different content of CH3CN have been calculated from a kinetic equation based upon a reaction scheme with two irreversible pseudo-first-order consecutive reaction paths. The values of k1/k2 are > 104 within CH3CN content range 1% – 80% v/v in mixed aqueous solvents. The intermediate hydrolysis product (B) exists in 72% dianionic, 27.9% monoanionic and 0.1% nonionic form under the present experimental conditions. Both dianionic and monoanionic forms of B are non-reactive while the nonionic form of B is reactive towards hydrolysis under such conditions.