Abstract <p>The effect of sonoplasma treatment on the generation of reactive oxygen and reactive chlorine species in waters of different salinity was studied. Chemiluminescent analysis and UV-visible spectrometry were employed to selectively detect and quantify the different types of reactive species. In distilled water, the sonoplasma treatment yielded 28.3 × 10^–4 M H₂O₂, but presence of NaCl caused a decrease in H₂O₂ yield. Sonoplasma treatment of the salt water yielded hypochlorite (ClO^–) as well, but its concentration did not exceed 1.2 × 10^–5 M and decreased with an increase in salinity. The degradation rate of model organic pollutants, methylene blue (MB) and methyl orange (MO) was analyzed in different sonoplasma treatment regimes. Kinetic analysis of the degradation revealed that, under plasma discharge, a direct decomposition of dyes occurs, while the contribution of reactive oxygen and reactive chlorine species generated during water plasmolysis is significantly lower. At the same time, the long-living H₂O₂ and ClO^– species are capable of decomposing the dyes even after the plasma treatment. The obtained results demonstrate the high efficiency of sonoplasma technology for the purification of both fresh and salt (up to 35 g/L NaCl) water and the importance of taking the salt concentration into account to optimize the purification process.</p>