Abstract: Electroless nickel deposits are incorporated as an interlayer between TiN coatings and mild steel substrates. The electroless nickel layer recrystallizes during r.f. sputtering and a coating assembly of TiN/Ni3/Fe is formed. The employment of electroless nickel results in an increase in the surface hardness as well as the adhesion strength. A Knoop surface hardness as high as 2120 HK5 (close to the hardness of bulk TiN) can be achieved in the interlayer-modified TiN coating.