Abstract: A tantalum coating process on 45 steel by chemical vapour deposition was studied in the Ta-Cl₂-H₂ system.Deposit rate of tantalum associated with temperature and partial pressure of TaCl₅ and H₂ was investigeted.Coating stru-ctures examined by metallogaphy,x-ray diffraction and electroprobe analysis methods ware also described.Corrosion experimental results in 37.7% HCl and 63% H₂SO₄ Solution show that corrosion rate of the coated samples is 2-3 ord ers lower then that of uncoated samples.