The paper presents a piezoelectric study, carried out at room temperature, for the Sr 1 − x Ba x Bi 2 Nb 2 O 9 ( x = 0, 15, 30, 50, 70, 85, 100 at%) ferroelectric (FE) ceramic system. The structural analysis has shown, for all the compositions, a pure orthorhombic phase with space group A2 1 am . A large electromechanical anisotropy phenomenon has been observed between the electromechanical coupling factors for the thickness and the planar vibrations, which could be very interesting for high‐frequency array transducers. The best values of piezoelectric parameters have been obtained for the Sr 0.70 Ba 0.30 Bi 2 Nb 2 O 9 composition. Our analysis of the X‐ray diffraction patterns around the (200) and (020) planes, before and after the polarization process, has suggested a better polarization process for barium concentrations of 15 and 30 at%, which provides higher piezoelectric properties.