The stability of piezoelectric scandium aluminium nitride (ScxAl1-xN) thin films with x= 27% was investigated after post deposition annealings up to 1000°C. The ScxAl1-xN thin films targeted for applications in micro-electromechanical systems (MEMS) were deposited close to room-temperature applying DC magnetron sputtering. Varying deposition parameters yielded films with different microstructural properties and piezoelectric constants. Upon annealing, the crystalline quality of thin films with c-axis orientation increased, as found via characterization techniques such as X-ray diffractometry and fourier transform infrared absorbance measurements. Additionally, piezoelectric constants after annealing steps up to 1000°C are reported as obtained via a Berlincourt measurement principle. Furthermore, modifications in chemical composition during temperature loads up to 1000°C were recorded by thermal effusion measurements.