Ni(II) naphthenate in gasoline or toluene shows a light green color，which is the result of absorption in the red and blue parts of the spectrum，the three bands due tO the spin-allowed d-d transitions are 403，680，and 1170 nm respectively．Ni(II) complex is octahedral complex． The naphthenate ligand attached tO Ni(II) can be exchanged for an alkyl group on isobutyla-luminium if Al／Ni in the mixture containing metalalkyl and naphthenate does not excecd the value of 0.53．At higher ratio (A1／Ni≥O．53)Ni(II) is reduced tO Ni(I) and (Ni(O)．In the mixture of Ni (II)with BF3·OE3 the naphthenate ligand is exchanged for halogen．The reac-tion produces Ni(II) complex，which is traced to the presence of three weak d-d bands and it is found to be octahedral complex as well as Ni(naph)2．The conclusions are analogous to the discussion on the basis of the measuring of magnetic susceptibility of the same nickel cata-lystic system．