Abstract: Seven π-cycllpentadinyl-bis (triphenylphosphine)- nickel( Ⅱ) hydroborates were synthesised by the reaction between hydroborate ions (B₁₂H₁₂^2-,B₁₀H₁₀^2-,B₁₁H₁₄^-, B₃N₈^-, B₁₀Cl₁₀^2-, B₁₀H₂Br₈^2-, B₁₀H₄I₆^2-) and π-C₅H₅NiPPh₃Cl in the presence of PPh₃. These compounds were characterized by elemental analysis, IR, and molecular conductivity.The thermal stability of these complexes was examined by DTAmethod.