Two different all nitrogen coordinated tungsten complexes, [W(N ^tBu)₂(NMe₂)₂] (1) and [W(N ^tBu)₂(NMe₂){(ⁱPrN) ₂C(NMe₂)}] (2) were compared for metal organic chemical vapour deposition (MOCVD) of tungsten nitride (WN) thin films in a state-of-the-art commercial MOCVD reactor. Precursor performances of both complexes were investigated under single source precursor (SSP) conditions and in the presence of ammonia as reactive gas where WN thin films were deposited on Si (100) substrates in a temperature range of 500-800°C. The X-ray diffraction (XRD) analysis showed that the films deposited under SSP conditions contained a mixture of carbide and nitride phases; while upon the addition of ammonia crystalline WN thin films were formed at higher temperatures (T ≥ 600°C). Elemental composition investigated by complementary techniques such as Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA) and X-ray photoelectron spectroscopy (XPS) revealed that the films grown in the presence of ammonia had increased levels of nitrogen and a decreased carbon content in comparison to films grown under SSP conditions. WN films deposited in the presence of ammonia show higher resistivity values than those deposited under SSP conditions.