Amavadin is a vanadium metallobiomolecule present in a few fungi Amanita that exhibits an unusual structure and coordination chemistry. This non-oxido-metal complex bears two particular N-oxyiminodicarboxylate ligands with single coordination bonds from all the eight donor atoms to the metal centre. Its biological role is yet unknown, although it mediates water oxidation and displays nitrite reductase-, catalase- and peroxidase-type activity, the latter on some thiols (including biological ones). Amavadin and its models can also catalyse peroxidative oxidation, peroxidative halogenation and carboxylation of alkanes and other hydrocarbons, as well as oxidation of alcohols, although under unlikely biological conditions. All these topics are addressed in this chapter.