This paper describes the synthesis and characterization of heteropolynuclear redox active materials [FerCuCl]4YY′, Y = Y′ = O, Y = Y′ = Cat and Y = O, Y′ = Cat, Fer = N,N-dimethylaminomethylferrocene and Cat = 3,4, 5,6-tetrachlorocatecholato ligand. Manometric O2 uptake measurements in PhNO2 show that tetranuclear [FerCuCl]4 and [FerCuCl]4Cat give the tetranuclear oxocopper(II) products [FerCuCl]4O2 and [FerCuCl]4CatO, respectively. The absence of carbonyl stretching vibrational bands in [FerCuCl]4Cat2 and [FerCuCl]4CatO suggest that tetrachloro-1,2-benzoquinone (TClBQ) is reduced to the corresponding catecholete during the oxidation of copper(I) centers in [FerCuCl]4. The near i.r. electronic spectra for [FerCuCl]4O2, [FerCuCl]4CatO and [FerCuCl]4Cat2 exhibit broad intense split maxima in the 750–875 nm range, attributed to a minimum of three halide ligands per Cu. Room temperature solid state e.p.r. spectra for [FerCuCl]4CatO and [FerCuCl]4Cat2 are of the axial type, suggesting a square pyramidal geometry around CuII.