Abstract The determination of selenium in the presence of tellurium and copper has been studied, to allow analysis of anodic slimes from electrolytic copper refining. Three methods have been developed for the determination of selenium in these slimes. They are based on the extraction of selenium with sodium sulphite, reduction of selenite with sodium sulphite, and separation of selenium and tellurium by adjustment of pH. Selenium (10 −3–10 −2 M) is determined in the presence of tellurium, copper, iron, silver and lead. The methods are fast and simple, do not need expensive reagents, and give satisfactory results.