This invention concerns biocides possessing fungicidal and bactericidal properties which can be used in construction, medicine and other various areas of technics. A nanostructural composition of biocide is realized from nanoparticles of bentonite powders intercalated by ions of Zn2+ and ions of Ag+ and/or ions of Cu2+. The biocides according to the invention are prepared starting from bentonite poweder which is preliminarly enriched with cations of Na+, then treated with 10-20% solutions of inorganic salts of Zn (preferably zinc chloride or zinc sulfate ZnSO4), and from bentonite powders preliminarly enriched with cations of Na+ and then treated with 10-20% solutions of inorganic salts of at least one ion selected in the group consisting of Ag+ ions (preferably silver nitrate) and Cu2++ ions (preferably copper sulfate). The powders of bentonite, intercalated with the Zn2+, Ag+ and/or Cu2+ ions, are .cleaned from acid anions and Na+ salts, and dispersed into nanoparticles mainly of no more than 70 nm.
