TiBCN films were deposited on Si(100) and cemented carbide substrates by using multi-cathodic arc ion plating in C_2H_2 and N_2atmosp~here. Their structure and mechanical properties were studied systematically under different N_2 flow rates. The results showed that the Ti BCN films were adhered well to the substrates. Rutherford backscattering sp~ectroscopy was employed to determine the relative concentration of Ti, B, C and N in the films.The chemical bonding states of the films were explored by X-ray photoelectron sp~ectroscopy, revealing the presence of bonds of Ti N, Ti(C,N), BN, pure B, sp~2C–C and sp~3C–C, which changed with the N_2 flow rate. Ti BCN films contain nanocrystals of Ti N/Ti CN and Ti B_2/Ti(B,C)embedded in an amorphous matrix consisting of amorphous BN and carbon at N_2 flow rate of up to 250 sccm. TiBCN films were deposited on Si (100) and cemented carbide substrates by using multi-cathodic arc ion plating in C_2H_2 and N_2atmosphere here. Their structure and mechanical properties were studied systematically under different N_2 flow rates. were adhered well to the substrates. Rutherford backscattering sp ~ ectroscopy was employed to determine the relative concentration of Ti, B, C and N in the films. chemical bonding states of the films were explored by X-ray photoelectron sp ~ ectroscopy, revealing the presence of bonds of Ti N, Ti (C, N), BN, pure B, sp ~ 2C-C and sp ~ 3C-C, which changed with the N_2 flow rate. Ti BCN films containing nanocrystals of Ti N / Ti CN and Ti B 2 / Ti (B, C) embedded in an amorphous matrix consisting of amorphous BN and carbon at N 2 flow rate of up to 250 sccm.