Polycrystalline beta-SiC is expected to be an excellent material for thin film temperature sensors for the measurement of the surface temperature of gas turbine engine components operated at high temperatures (up to 1500 degrees C). In this paper, Vickers and Knoop indentation microhardness tests were carried out on the silicon carbide films grown on Si(100) substrates by the activated reactive evaporation (ARE) process to measure one of the important mechanical properties, i.e. hardness of the films. The results of these tests are presented as a function of the ARE process parameters, such as C2H2 pressure P-C2H2, substrate temperature T-sub, ARE electrode voltage V-ARE for the generation of d.c. glow discharge and substrate bias V-sub. It was found that the hardness of the films is very much dependent on these process parameters. A Vickers hardness value of 3680 kgf mm(-2) (36.1 GPa) at 25 gf load (0.25 N) and a Knoop hardness value of 2060 kgf mm(-2) (20.2 GPa) at 100 gf load (0.98 N) are obtained for polycrystalline beta-SiC films (C-to-Si ratio, 1.17) prepared under the following deposition conditions : C2H2 pressure, 3 mTorr (0.4 Pa); substrate temperature, 700 degrees C; ARE electrode voltage, +150 V; substrate bias, -50 V. Microhardness variation of the beta-SiC films with applied load on the indenter was also studied. It was found that the hardness of the films decreases with increasing load, which is believed to be due to indentation size and substrate hardness effects.