In this study the extraction of nickel, from aqueous NiCI2 and NiSO4 Solutions with octa- noic, decanoic and lauric acid dissolved in kerosen was investigated within the pH range of 6-8. The probable compositions of the complex structure was determined by statistical method. The calculations suggest that with 0.5 M octanoic acid, 0.5 and 1 M decanoic acid dimeric complexes are formed. The number of solvating acid molecules per metal ion 0,1 or 2. With 1 M octanoic acid it forms monomeric and dimeric complexes. The number of sol-vating acid molecules per metal ion is found to be 0,1 or 2. Monomeric complexc3 are formed with 0.5 M lauric acid. The number of solvating acid molecules per metal ion is 0 or 1.