Background Chlorine dioxide (ClO 2 ) is an inorganic, potent biocide and is available in highly purified aqueous solution. It can be administered as an oral antiseptic in this form. Objectives Our aim is to determine the level of inflammatory markers and cytochrome genes expressed by enterocytes exposed to different concentrations of hyperpure chlorine dioxide solution. Methods Porcine jejunal enterocyte cell (IPEC‐J2) cultures were treated with the aqueous solution of hyper‐pure chlorine dioxide of various concentrations. We determined the alterations in mRNA levels of inflammatory mediators, such as IL6, CXCL8/IL8 , TNF , HSPA6 (Hsp70) , CAT and PTGS2 (COX2) ; furthermore, the expression of three cytochrome genes ( CYP1A1 , CYP1A2 , CYP3A29 ) were analysed by quantitative PCR method. Results The highest applied ClO 2 concentration reduced the expression of all three investigated CYP genes. The gene expression of PTGS2 and CAT were not altered by most concentrations of ClO 2 . The expression of IL8 gene was reduced by all applied concentrations of ClO 2 . TNF mRNA level was also decreased by most ClO 2 concentrations used. Conclusions Different concentrations of chlorine dioxide exhibited immunomodulatory activity and caused altered transcription of CYP450 genes in porcine enterocytes. Further studies are needed to determine the appropriate ClO 2 concentration for oral use in animals.