Nanostructured titanium aluminium nitride ( TiAlN ) thin films were prepared on Si (111) substrate by reactive DC magnetron sputtering technique for various N 2 flow rates. X-ray diffraction showed that the films are nanocrystalline and the grain size decreases from 14 nm to 5 nm as the N 2 flow rate is increased. The thermal properties are then studied by photoacoustic (PA) spectroscopy. The study revealed an increase in thermal diffusivity and conductivity with increasing N 2 flow rates, and the measured values of the thermal properties are significantly lower than those obtained with bulk materials which constitute TiAlN .