The paper shows the results of comparative investigations of taps with single-layer coatings - TiN, (Ti, Zr)N, (Ti, Al, V)N and with double-layer coatings TiN-IC and TiN-BN with outer layer in the form of amorphous carbon or amorphous boron nitride. The coatings were put on taps (made of HSS 6-5-2) in temperature below 700 K. The gray cast iron 250 (according to ISO standard) was the material for exploitation investigations. The investigations results of the tool life enabled to formulate proper conclusions with regard to usefulness of investigated coatings in gray cast iron tapping. The best results were for applying single-phase layer (Ti, Zr)N.