Abstract: The present invention relates to a method for selectively precipitating and extracting gold in aqueous solution by niacin. Aqueous Au3+ is precipitated selectively as it's complex from gold containing acidic mixtures by biomolecule niacin, with the formula [AuCl4]?[2Niacin+H]+. After precipitation, the complex is separated from impurities by filtration. Recovered complex is reduced by using a reductant like sodium metabisulfite (Na2S2O5) to recover gold metal. The method is highly cost-effective, sustainable and recovers about 96.5% of gold in 2 minutes from an electronic waste composed of Au. Cu and Ni. The method is also employed to extract gold from nanomaterials waste generated in laboratories.