Abstract <p>Kinetic regularities of nucleophilic substitution reactions at electron-deficient centers (phosphorus and sulfur) in organized microheterogeneous systems based on cationic surfactants and α-nucleophiles―hypobromite and hydroperoxide ions―have been analyzed in terms of the pseudophase distribution model. The contribution of the concentration effects of substrates (4-nitrophenyl esters of phosphonic, phosphorous, and toluenesulfonic acids) and nucleophiles (HOO^– and BrO^– anions) has been quantitatively evaluated on the basis of reactant binding constants. The contribution of the microenvironment has been assessed using the second-order reaction rate constants in water (<i>k</i>^w_2,HOO–, <i>k</i>^w_2BrO–, M^–1 s^–1) and in the micellar pseudophase (<i>k</i>^m_2,HOO–, <i>k</i>^m_2,BrO–, M^–1 s^–1). The significance of the “trivial” concentration effect in micellar catalysis has been established.</p>