Atomic structure, electronic structure and properties of ZrBCN materials were studied using ab-initio calculations. We focus on the effect of N and Zr content and compare our results with the characteristics of samples prepared by reactive magnetron sputtering. We find that the materials are characterized by a mixture of covalent and metallic bonding. The metallic-to-covalent ratio is primarily controlled by the N content, and well correlated with measured electrical resistivity. Zr-N bonds have the highest preference to form out of all bonds in the ZrBCN system. Hard nanostructure forms at high Zr and low N content, containing (i) pure ZrN and (ii) (theoretically predicted and experimentally observed) solid solution close to ZrB0.50N0.50. The results allow one to tailor ZrBCN compositions which can combine different functional properties, such as high thermal stability, high hardness and electrical conductivity. (C) 2013 Elsevier B.V. All rights reserved.