The article proposes using the agricultural waste of Cashew Nuts Shells (CNS) from the Republic of Côte d’Ivoire to produce activated carbon used in water treatment by physical activation. Washed and crushed CNS was carbonized at 800 °С. The obtained crushed and charred CNS was physically activated with water vapor within the temperature range of 400 to 700 °С. Specific surfaces (SBET) and porous structures of obtained activated carbon samples were investigated by low-temperature nitrogen absorption using X-ray diffraction (phase) analysis. The results showed that an increase in the activation temperature with a fixed activation time leads to larger material specific surface, microporous structure development and higher total volume of mesoand micro pores of activated carbons obtained. The X-ray phase analysis results demonstrated that the degree of graphitization, interlayer spacing and crystallite size change insignificantly. It was shown that CNS can be used for activated carbon production that is not inferior by its sorption properties to analogues currently used for water purification.