enhanced in a linear fashion by each of Triton X-100 (TX100), Triton X-305 (TX305), Brij 35, and sodium dodecyl sulfate (SDS). Solubility enhancement efficiencies of surfactants above the critical micelle concentration (CMC) follow the order of TX100> Brij 35>TX305>SDS. PAHs are solubilized synergistically in mixed anionic-nonionic surfactant solutions, especially at low surfactant concentrations. The synergistic pwer of the mixed surfactants is SDS-TX305>SDS-Brij35>SDS-TX100. Synergistic effect of a given mixed-surfactant solution on different PAHs also appears to be linearly related to the solute logKow. The noted synergism for the mixed surfactants is attributed to the formation of mixed micelles, the lower CMC of the mixedsurfactant solutions, and the increase of the solute s molar solubilization ratio or micellar partition coefficients ðKmcÞ because of the lower polarity of the mixed micelles. Suitable quantity of inorganic cations can enhance the solubilization capacities of anionic–nonionic mixed urfactants, the effect being Mg2+>NH+4>Na+. The water solubility of pyrene was slightly increased by anthracene and significantly increased by 1,2,3-TCB in the presence of SDS-Brij 35. Mixed surfactants may mprove the performance of surfactant-enhanced remediation of soils and sediments by decreasing the applied surfactant level and thus the remediation cost.