Stresses in Al-1.0 wt.% Si/TiW thin films structure on Si(100) substrate were determined during thermal cycles by the curvature measurement technique. It was found that during heating the thermal strains are elastic up to about 90 degrees C with compressive yield stress of about 200 MPa and biaxial elastic modulus of about 187 GPa. Above 90 degrees C the films undergo plastic deformation in which the compressive stress decreases linearly with increasing temperature. During the third and fourth thermal cycles TiSi and TiSi2 are formed at the Al/TiW interface leading to a decrease in the compressive stress by about 130 MPa. Thr influence of composition and microstructure changes on the stresses is discussed.