Aim: To analyze published data on the distribution, stocks of brown and red algae in the White and Black Seas, as well as on the chemical structure and properties of polysaccharides and their use. Evaluate the effectiveness of chemical-technological research and its results.Methods used: In preparing the review, science-metric methods of literature analysis from the databases of the RSCI, Scopus were used, as well as our own published research results, which used the methods of IR spectroscopy, carbon‑13 nuclear magnetic resonance (13С-NMR) and standard methodsResult: A review of the scientific literature on the distribution, stocks and use of algae in the White and Black Seas of the coastal zones of Russia are presented. Data on the study of the chemical composition, technological properties and chemical structure of polysaccharides from the White Sea brown algae — Fucus vesiculosus and Ascophyllum nodosum, as well as Gongolaria barbata, Ericaria crinita — Black Sea and red algae A. plicata of the White Sea and 2 species — Coccotylus brodiei and Phyllophora crispa of the Black Sea.Novelty: Alginates from Cystoseira have been shown to contain about 35% L-guluronic acid. The chemical structure of the polysaccharide from Phyllophora crispa has been confirmed as kappa-omega-carrageenan. The prospect of using A. plicata residues after agar extraction and their processing as secondary raw materials to obtain microcrystalline cellulose, nanocellulose or amino acid hydrolyzate was shown.Practical significance: The presented data on the distribution of algae stocks and the recommended yield (RY), their chemical composition, as well as the structure and properties of polysaccharides can be used to draw up recommendations for regulating fisheries and planning production.