This work targets the development of high frequency SAW devices on Sc 0.3 Al 0.7 N/Si as well as on thin Sc 0.3 Al 0.7 N membranes, with applications in temperature sensors devoted to harsh environmental operation. Advanced nano-lithographic and micromachining techniques have been used for device manufacturing. Rayleigh and Sezawa modes (on Sc 0.3 Al 0.7 N/Si structures) respectively Rayleigh and Lamb mode (on Sc 0.3 Al 0.7 N membranes, 0.8 μm thin) have been evidenced. The sensitivity and temperature coefficient of frequency (TCF) have been experimentally determined and analyzed. A simulation technique that combines Finite Element Method (FEM) with Coupling of Modes (COM) was used for the determination of the resonance frequencies. The mode shapes of the resonances that appear in the bulk devices (supported on Sc 0.3 Al 0.7 N/Si) as well as in the thin Sc 0.3 Al 0.7 N membrane supported structures, were evidenced by FEM. Simulations performed for the temperature dependence of the resonance frequency led to results very close to the experimental ones for the Rayleigh mode for devices supported on bulk substrate.