The corrosion protective properties of TiN coatings deposited on low carbon and stainless steel substrates have been studied by electrochemical methods in 3% NaCl and 0.5 M H2SO4. The coatings have been deposited by are plasma evaporation. The discharge current and NZ pressure were varied in the range from 100 A to 160 A and from 5 x 10(-4) mbar to 8 x 10(-3) mbar respectively. Ion implantation of some thin coatings has been carried out with boron ions at doses 1 x 10(16), 5 x 10(16) and 1 x 10(17) ions cm(-2). The film structure has been analysed by X-ray diffraction and scanning electron microscopy. Coatings thicker than 8 mu m, deposited at nitrogen pressures of 1 x 10(-3) and 5 x 10(-4) mbar have some protective effect. TiN thin layers with thickness 4-5 mu m accelerate the substrate dissolution in 0.5 M H2SO4. All TiN coatings reduce considerably the values of the anodic current density measured for the system "low-carbon steel substrate-TiN coating" in 3% NaCl and change the corrosion and the pitting formation potentials to more positive values. Implantation of thin titanium nitride coatings shows negligible positive effect on the electrochemical behaviour.