Technical lignins were modified in order to improve their lipophillic properties, to develop porosity and to increase the matrix surface affinity towards selected contaminants. With this aim, the incorporation of Si-contaning building blocks into lignin matrix was accomplished using mild sol-gel process. The siliceous lignin-based products obtained (Si-lignins) were characterized by elemental and functional analysis, spectroscopic techniques (29Si- and 13C solid state NMR, FTIR and XPS), nitrogen gas, normal paraffins and water vapors adsorption/desorption isotherms. Sorption tests with potential contaminants (copper and manganese ions, and 2,4-pesticide) and a set of biological tests were performed to characterize the targeted properties of Si-lignins.