The impact of sodium dodecyl sulfate (SDS) on the protonation equilibria of 5-sulfosalicylic acid and 5-Hydroxysalicylic acid has been studied in various concentrations (0.0−2.5% w/v) of sodium dodecyl sulfate solution maintaining an ionic strength of 0.16 mol dm −3 Nacl at 303 K. The protonation constants have been calculated with the computer program MINIQUAD75 and the best fit models are arrived at based on statistical grounds employing crystallographic R factor, χ 2 , skewness, and kurtosis. These protonation constants values have been found to shift in micellar media as compared to those in pure water. The differences in the values have been attributed to the solvent properties of the interfacial and bulk phases involving contribution from the micellar surface potential in the case of charged micelles. The trend of log values of stepwise protonation constants with mole fraction of the medium have been explained based on electrostatic and non-electrostatic forces operating on the protonation equilibria. Distributions of species, protonation equilibria, and effect of influential parameters on the protonation constants have also been presented.