Bis(diphenyldithiophosphinato)iron(II) (2) is synthesised by the action of (C6H5)2PS2H on FeCO3. Spectroscopic data show that2 has got a distorted tetrahedral structure. The ligand field strength in2 (5748 cm−1) as determined from the diffuse reflectance spectrum is comparable to that in reduced rubredoxin (6250 cm−1). The isomer shift value in the Mossbauer spectrum of2 also is quite consistent with that reported for reduced rubredoxin and other iron(II) tetrahedral compounds. In solution and in the presence of air2 is spontaneously oxidised to the ferric complex [(C6H5)2PS2]3Fe (1). The dark green1 is reduced to the pale yellow ferrous complex2 by the action of NaBH4 inthf solution. This redox behaviour is comparable to that of rubredoxin, although the oxidised complex differs from oxidised rubredoxin in that it has got octahedral geometry compared to the tetrahedral geometry of the oxidised rubredoxin. The reaction of1 with 2,2′-bipyridyl, NH3, Br2 and NO and the Mossbauer spectra of the products are also described here.