The names of the six new elements (Nihonium, Moscovium, Tennessine, Oganesson, Livermorium, and Flerovium) were decided by the International Union of Pure and Applied Chemistry (IUPAC).

The IUPAC is the global authority on chemical nomenclature, terminology, standardization, and measurement. They are responsible for reviewing proposed names for new elements and ensuring they adhere to their guidelines.