Infectious diseases are the leading cause of morbidity and mortality in the human population. The causative agent for the development of multidrug-resistant bacteria is one of the most acute health problems. The rise in antibiotic resistance is also associated with the lack of new antimicrobials. Purpose: to obtain hydro/alcohol sols of metal nanoparticles with long-term bactericidal action. Materials and methods. Hydro/alcohol sols were obtained in distilled water/ alcohol by arc electric discharge passing through two electrodes: Ag, TiO2, Fe3O4, VO2, CoO, TaO2, ZnO, CuO, a combination of TiO2 + Al2O3 + MoO2. The studies hydrosols of metal nanoparticles CuO, TaO2, Fe3O4, TiO2, Ag, ZnO were carried out on cultures of microorganisms S. aureus, P. aeruginosa, P. vulgaris, S. tiphimurium, C. albicans, E. coli. The hydrosols CuO, TaO2, Fe3O4, TiO2, ZnO contain cetylpyridinium chloride (CPC) as a stabilizer — 0.07%, in the hydrosol Ag the stabilizer is sodium citrate (E331). The observation period is 14 days. Results. Metal hydrosols are bactericidally active in a whole solution of 2.4—13.88 mg/L. Conclusions. A method for obtaining hydro/alcohol sols of nanodispersed systems of metals Ag, TiO2, Fe3O4, VO2, CoO, TaO2, ZnO, CuO, a combined solution of TiO2, Al2O3, MoO2 has been developed. Hydrosols CuO, TaO2, Fe3O4, TiO2, ZnO, demonstrate long-term bactericidal activity for 14 days. © 2023 Clinical Dentistry LLC. All rights reserved.