The aim of the studies was to examine the applicability of volcanic tuff as a corrosion inhibitor in aqueous systems and to identify the mechanisms owing to which the tuff is acting as an inhibitor of corrosion. The scope of research includes: examinations of the structure and selected properties of the tuff from Filipowice, including fractographic examination of the Filipowice tuff rocks, X-ray diffraction analysis, and thermal analysis; study of the corrosion resistance of DC01A low-carbon steel in aqueous systems without and with inhibitor, which is volcanic tuff.