Abstract <p>Tensiometric and dilatational rheological characteristics of mixed solutions of dicationic diimidazolium surfactants with extremely short spacer fragments and anionic surfactants (sodium dodecyl sulfate, sulfonol, sodium 3-laureth sulfate) at the interface with air have been studied by the pendant drop shape and oscillating pendant drop methods. The character of the interaction between the dicationic and anionic surfactants depends on the structure of anionic surfactant molecules. It has been shown that strong complexes with a component ratio close to 1 : 1 can be formed between the dicationic surfactant containing four methylene groups in the spacer fragment and sodium dodecyl sulfate. It has been found that the resulting complexes are stable in the neutral and weakly acidic pH regions.</p>