High performance liquid chromatography (HPLC) may be used for analysis of municipal wasterwater containing ethoxylated alcohol surfactants. After cleanup of the sample by XAD‐2 resin, liquid‐liquid extraction, ion exchange and cobalt thiocyanate extraction, the surfactant is derivatized with phenyl isocyanate to permit UV detection and analyzed by both normal phase and reversedphase HPLC. The alkyl chain length distribution is determined using reversed‐phase HPLC, while the ethoxy chain length is determined by normal phase HPLC. The limit of quantification is 0.1 ppm.