In recent years, the functional polymeric compounds are broadly used to modify the silica surface, which allows one to obtain the corresponding organo-mineral composites having sufficiently high capacity while maintaining good kinetic characteristics peculiar to inorganic adsorbents. In this respect, application for these purposes functional biopolymers, such as amino- and sulfo-containing polysaccharides chitosan and carrageenan, are of great interest. Hybrid materials were prepared using various synthetic methods: adsorption and covalent binding of polymer on the silica, forming of inorganic matrix in polymer solution (sol gel method). The effect of route of polymer coating creation on thermal stability and ability to degradation, surface morphology, including pore size distribution and average surface area, as well as other physicochemical characteristics of such hybrid biocomposites have been described. The composite synthesized by covalent binding of chitosan on the silica surface was found to show high adsorption activity with respect to milligram amounts of toxic metal oxoanions and moderately adsorbed cations. Thus, the composite extracted metal ions Zn(II), Cu(II), Cd(II), Pb(II) and Fe(III) with adsorption capacity range from 0.03 mmol/g for Fe(III) to 0.17 mmol/g for Zn(II) in the neutral medium, and adsorbed oxoanions V(V) and Mo(VI) from the acidic medium with adsorption capacity 1.6 and 1.5 mmol/g, respectively, and 0.5 mmol/g for Cr(VI) at neutral pH. Moreover, it was found that after functionalization of the surface of organomineral composite with iodoacetic acid, adsorption capacity are highly increased with respect to studied cations of heavy metals up to the range from 0.14 mmol/g for Pb(II) to 0.60 mmol/g for Zn(II) in the neutral medium. Effect of polysaccharide nature on the adsorption of cationic and anionic dyes was studied. The chitosan-silica composite was found to be effective towards sulfonated azo dyes: Orange II and Acid Orange 8 (0. 20 mmol/g), Orange G (0.12 mmol/g), Acid Red 88 (0.48 mmol/g) and Acid Red 1 (0.09 mmol/g). Composite carrageenan-silica has shown the highest adsorption capacity towards cationic synthetic dyes: Bismark Brown (0.54 mmol/g), Acridine Orange (0.88 mmol/g), Malachite Green (0.55 mmol/g), Methylene Blue (0.61 mmol/g), Crystal Violet (0.52 mmol/g).