The degree of isomerization in the alkyl chain of ethoxylated alkylphenol surfactants influences the retention time in a HPLC silica column and the partitioning coefficient between n-heptane and water. HPLC analysis of isomer species with different alkyl groups allows the deduction of some general trends in the influence of isomerization and branching on the surfactant properties. The alkyl group interaction with the solvent and the heptane-water partitioning data show that direct interaction between the surfactant "tail" and the solvent is also of importance.