Unexpected behavior of thallium atoms, produced in a reaction of gold target with accelerated ³He ions, in liquid–liquid extraction with [C_nmim][NTf₂] ionic liquids (n = 2, 4, 6–8, 10) was investigated. Contrary to the general expectations, a significant proportion of thallium produced in the nuclear reaction was found in a non-monovalent state upon dissolution of the KCl aerosol collector. This finding is critical for the design and evaluation of the forthcoming chemistry experiments with the superheavy element nihonium.