The methanolysis of ionized phenyl salicylate, PS-, has been studied in the absence and presence of 0.03 M cetyltrimethylammonium bromide, CTABr, at 0.01 M NaOH and within the CH3OH content range of 10−80 or 90% (v/v). The pseudo-first-order rate constants, kobs, remain unchanged with change in [CTABr]T from 0.0 to 0.03 M at ≥65% (v/v) CH3OH. The ratio, kobs(0.0 M CTABr)/kobs(0.03 M CTABr) decreases from 4.6 to 1.1 with increase in CH3OH content from 10 to 60% (v/v). At the constant temperature and [CH3OH]T, the rate constants, kobs, show a decrease with increase in [CTABr]T. These results are explained in terms of a pseudophase model of micelle. At 30 °C, the pseudo-first-order rate constants, for the reaction of CH3OH with PS- in the micellar pseudophase and cmc of CTABr increase from 9.63 × 10-4 and 1.8 × 10-4 to 78.8 × 10-4 s-1 and 60.0 × 10-4 M, respectively, while the binding constants, K1, decrease from 8080 to 39 M-1 with increase in methanol content from 10 to 50% (v/v). Similar results are obtained at different temperatures ranging from 25 to 45 °C. The activation parameters, ΔH* and ΔS*, for are larger than those for (where represents pseudo-first-order rate constant for the reaction of CH3OH with PS- in the nonmicellar pseudophase) at 10, 20, and 30% (v/v) CH3OH. These results are attributed to the increased ground-state stability of a monomeric methanol in the micellar pseudophase compared to that in the nonmicellar pseudophase. The thermodynamic parameters, ΔH0 and ΔS0, for binding constant, K1, reveal the decrease from −8.6 and −10.5 to −14.1 kcal/mol and −31.9 cal/(K mol), respectively, with increase in CH3OH content from 10 to 30% (v/v). Significantly lower values of compared to those of at low contents of CH3OH are ascribed to (i) reduced [CH3OH] in the micellar pseudophase, where PS- molecules exist, compared to [CH3OH] in the nonmicellar pseudophase and (ii) partial loss of the efficiency of intramolecular general base catalysis due to probable ion-pair formation between anionic site of micellized PS- molecule and the cationic micellar headgroups.