Abstract <p>Cocamidopropyl betaine (CAPB) is an amphoteric surfactant widely used in personal care and cleaning products, including swimming pools. CAPB present in pool water may act as a precursor of the formation of disinfection by-products under conditions of water chlorination. The study developed an approach to the highly sensitive determination of the main components of cocamidopropyl betaine in pool water using high-performance liquid chromatography with detection by high-resolution mass spectrometry (HPLC–HRMS). The use of solid-phase extraction as a sample preparation method made it possible to achieve limits of detection at a level of 0.1 ng L^–1. The developed approach was successfully tested in the analysis of real pool water samples. The obtained data demonstrate that all target analytes were present in pool water extracts and their concentrations were in the range from 0.90 ± 0.10 to 124 ± 6 ng L^–1. This necessitates regular monitoring of the content of CAPB of pool water and the development of sanitary and hygienic standards.</p>