Аннотация:The size and structural modification of antibacterial drug substance was made using cryochemical method, The method was made by the formation of molecular vapor flow combined with a carrier gas stream, and followed by condensation of substance molecules on a cold down to 80 K surface. Using this method, the synthesis of nanoforms of the antibacterial drug dioxidine was carried out. It is recorded that the molecular structure of the drug remains unchanged uring cryochemical size and structural modification. A regular decrease in particle size and change in the crystal structure of cryochemically modified dioxidine with an increase in the value of the carrier gas flow (CO2) was found.