The synthetic zeolite-sodalite obtained by the hydrothermal conversion of fly ash with aqueous sodium hydroxide was used in the experiments. Its adsorption properties in relation to lithium ions were examined. The effects of: solution pH, presence of polymeric substance – poly(acrylic acid) and order of individual adsorbates addition were determined. To specify the binding mechanism of lithium ions on the sodalite surface, besides adsorption experiments, the measurements leading to the solid surface charge density and zeta potential determination, were performed. As a result, the structure of mixed adsorption layer composed of polymer+metal complexes was characterized. The presented study concerns two important issues: management of environmentally harmful wastes such as coal combustion products as well as searching for new sources of lithium and effective methods of its acquisition.