A nonlinear theory based on the notion of oriented continuum is presented with a view to describing piezoelectric powders. The generalized kinematics comprehends the macroscopic motion of grains as well as the internal deformation (rotation, stretch) of grains (via a so‐called director field) in connection with local electromechanical interactions. A complete set of coupled dynamical electroacoustic equations is deduced from first principles for this class of granular media. Thermodynamical arguments then allow one to construct general constitutive equations that exhibit both thermodynamically reversible and irreversible processes. Of necessity, the theory is first constructed in a fully nonlinear framework. In a second stage, the nonlinear equations are perturbed, by means of a Lagrangian variation, about a free finite initial state in which the directors are randomly oriented. These initial privileged directions provoke a local breaking of the ideal symmetry of the material and there results a nonhomogeneous medium. In addition, in the perturbed equations thus obtained, nonlinear terms related to ponderomotive couples and orientational electromechanical couplings are involved. Among the equations obtained, one governs the internal deformations of grains, which materialize in a microgyration of grains about their center of mass and a microstretch in the direction along which the local electromechanical interactions take place. This work collects all the essential ingredients which are required in a study of physically interesting phenomena such as memory echoes in resonant piezoelectric powders.