Photolysis experiments were performed to quantify the effect of three anionic surfactants on the photolysis of hydrogen peroxide (H2O2) at the ambient laboratory temperature of 22+/-1 degrees C. H2O2 photolysis in water, methanol, and surfactant monomeric solution was also conducted to compare the photochemical reactivity of H2O2 in different media. Photolysis rates were highest for water, followed by micellar solutions, and lowest for methanol. The results show that the photochemical reactivity of H2O2 is less favorable in organic solvent than in water and surfactant micelles affect H2O2 photolysis. Retarded photolysis of H2O2 in micellar solutions implies that a fraction of H2O2 dissolved in water partitions into micellar pseudophase of surfactant. H2O2 partitioned into micelles has less photochemical reactivity and thus photolysis rate was retarded in the presence of micelles. Photolysis inhibitory level by micelles was shown to be dependent on the kinds of surfactants used in this study. In addition, the inhibitory effect by surfactant monomers was negligible due to the absence of micelles.