The dependence of the dielectric permittivity on the uniaxial compressive stress was investigated for the case of Na 0.5 Bi 0.5 TiO 3 –KTaO 3 ceramics. Special attention was focused on the reversibility of the permittivity–stress dependence. The results were connected with the transition from the ferroelectric to the relaxor state in the concentration region between 5 and 10mol% of KTaO 3 . With this transition, the permittivity–stress dependence changes from non-linear, irreversible and time dependent to linear, instantaneous and reversible. In samples with 10–30mol% of KTaO 3 some minor relaxations were observed, which were suppressed under a small pre-stress. The stress sensitivity was higher at a lower measuring frequency and the reversible change of the permittivity was the highest in the sample with 20mol% of KTaO 3 (the absolute and relative changes of permittivity were 196.5 and 10.3%, respectively, at a pressure change between 8 and 219MPa). The obtained results are discussed in terms of the macrodomains/microdomains’ reorientation under applied pressure and the transition from one to another with a change of the KTaO 3 concentration. The use of Na 0.5 Bi 0.5 TiO 3 –KTaO 3 ceramics for device applications is described.