The influence of cationic, anionic, and non-ionic surfactants and co-surfactants on the equilibrium in the system: caprolactam in the 1,0% (NH4)(2)SO4 aqueous solution-toluene was investigated. An insignificant effect of surfactant on the distribution coefficient of caprolactam was observed. However, a considerable increase of the distribution coefficient was indicated when n-butyl alcohol or octyl alcohol were added to the caprolactam water solution in the presence of SDS.