The paper presents a piezoelectric study, carried out at room temperature, for the Sr1 − xBaxBi2Nb2O9 (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 A21am. 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 Sr0.70Ba0.30Bi2Nb2O9 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.