Electrospinning from a capillary is one of the methods for the production of nanofibers. The specific properties of such fibers result first of all from their large specific surface and the high porosity of the fiber mat. This article presents a process for producing functional nanofibers with antimicrobiological properties by electrospinning from polyacrylonitrile/dimethyl sulphoxide solution containing a bioactive agent based on quaternary ammonium salts (N, N, n, n,-didecyl-N, N-dimethylammonium chloride, Bis-(3-aminopropyl)-dodecylamine) and 2-propanol. The structure of the nanofibers obtained and their antimicrobial activity are investigated. A 5 wt % addition of bioactive preparation to the polymer solution (concentration of active substance in solution about 1.5 wt %) makes it possible to obtain fibers showing good bactericidal properties. After 6 h in contact with these fibers, Escherichia coli are eliminated to a level of 99.84% and Staphylococcus aureus to 99.99%. The IR spectrophotometric measurements do not indicate a residue of solvent in the bioactive nanofibers and show an increase in content of CH and CH2 groups in relation to the pure nanofibers, which is connected with the presence of the biocide. Their degree of crystallinity determined by the X-ray scattering method is 44.4%. The nanofibers obtained can be designed for medical and filtration applications. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 767-775, 2013