Anions of heterocyclic 5-hydroxy-4H-pyran-4-ones coordinate to the iron(III) central atom forming tris(O,O-chelate)iron(III) complexes. The complexes are redox stable in the dark, their irradiation leads to the photoreduction of Fe(III) to Fe(II) associated with oxidation of a ligand to its radical. The efficiency of the photoredox process is strongly wavelength dependent and influenced by the peripheral 2-CH 2 R and 6-CH 3 groups of the ligands. The results on electrochemical properties of the free anions and the complexes are given also. Relations between the electronic properties of the peripheral groups R, redox potential values and quantum yields of the photoreduction are reviewed.