The present paper reports on the influence of Si addition on the properties, namely stresses and thermoelastic behaviour, of r.f. reactive magnetron sputtered TiN coatings, in order to reach a further increase of coating performance in industrial application. Residual stresses were determined by two distinct methods, one of them being the so-called mechanical method. In this method, the deflection of the substrates, before and after deposition, is measured using a high precision co-ordinate measuring unit as well as an interference optical microscope (deflection method). The second method used is X-ray diffraction using the sin(2)psi method. By heating the samples and in situ observation of substrate deflection evolution with temperature, the analysis of thermally-induced stresses was also carried out. Regarding the results, compressive residual stresses up to approximately 11 GPa were observed. The stress magnitude was found to depend on the total amount of Si addition to TiN matrix; for large Si additions (> 12 at.%) a significant reduction was observed. Furthermore, the analysis of thermally-induced stress allowed the determination of the real effective deposition temperature, which led to a value of approximately 200 C for the conditions employed within this work.