Abstract: A new type of actuator using functionally graded piezoelectric ceramics can produce large out of plane displacements, reduce mid-plane stresses and avoid failure from internal debonding or from stress peaks. A functionally graded piezoelectric ultrasound transducer has a broadband frequency characteristic. This study presents a simple and accurate high order theory to examine the electromechanical behaviour of piezoelectric generic shells with thickness-graded material properties. The displacement components are assumed to be a linear function of the shell thickness, while the electric potential is taken as a quadratic distribution through the thickness coordinate. Both equations of motion and boundary conditions of the shells are simultaneously obtained using the variational principle. Different types of charge equilibrium equations are considered, which correspond to the respective driving power when it is acted as actuators. The Fourier series method is then applied to obtain the analytical solution of mechanical and electric fields of functionally graded piezoelectric shells. These newly derived equations can be reduced to many typical structures as beam, plate and circular cylindrical shell. In terms of analyzing a simply-supported inhomogeneous and laminated piezoelectric plate, numerical results of the proposed formulation coincide well with exact solutions in previous literature. Finally, numerical studies are performed to examine the electromechanical responses of functionally graded piezoelectric circular cylindrical shells. The effects of graded material properties on the displacement, stresses and electric potential are clearly exhibited. This piece of work was motivated by the increased general use of functionally graded materials and piezoelectric materials and also a need to understand the electromechanical behaviour of functionally graded piezoelectric materials.