In this work Hf–C–N coatings were deposited on silicon substrates by reactive R.F. magnetron co-sputtering from two hafnium and carbon targets in a reactive nitrogen atmosphere at various negative bias voltages from 0 to 150 V. The effect of the bias voltage on the chemical composition, crystalline structure and mechanical properties was studied by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD) and nanoindentation. The results show that the obtained films have a Hf/(C + N) ratio of around 1 and present an evolution with the bias voltage from a quasi-amorphous structure, with a low hardness (6 GPa) to crystalline Hf 2 CN films with a high hardness (23 GPa) and electrical resistivity values in the order of 10 4 Ω·cm − 1 . This study shows the potential for hard and electrically conductive Hf–C–N films in industrial applications.