This issue of the journal presents contributions from the 5th International Sol–Gel Conference of CIS countries. It is a traditional biennial event held alternately in turn in Russia, and then in one of the CIS countries. The fifth, anniversary CIS Sol–Gel 2018 conference was carried out in the end of August 2018 in St. Petersburg. Its major organizer was the Institute of Silicate Chemistry of the Russian Academy of Sciences, a major research center in this field in the North-West of Russia and the initiator of this conference series. The conference agenda covered theoretical aspects of the sol–gel process, challenges in the sol–gel synthesis, and preparation of nanoparticles, films, coatings and membranes, hybrid inorganic and organic–inorganic composites, xerogels, glass and bulk ceramic materials. Strong focus was set on the use of sol–gel synthesis in the field of environmental protection, agriculture, and biomedicine.