This thesis describes the design of low frequency, high power capability class-I flextensional, otherwise known as the barrel-stave, flextensional transducer. Piezoelectric ceramic rings are inserted inside the shell. Under an electric drive, ceramic rings vibrate in the thickness mode in the longitudinal axis. The longitudinal vibration of the rings is transmitted to the shell and converted into a flexural motion. Low amplitude displacements on its axis create high total displacement on the shell, acting as a mechanical transformer. Equivalent circuit analysis of transducer is performed in MATLAB and the effects of structural variables on the resonance frequency are investigated. Critical analysis of the transducer is performed using finite element modeling (FEM). Three dimensional transducer structure is modeled in ANSYS, and underwater acoustical performance is investigated. Acoustical analysis is performed by applying a voltage on piezoelectric material both in vacuum and in water for the convex shape barrel-stave transducer. Effects of transducer structural variables, such as transducer dimensions, shell thickness, shell curvature and shell material, on the electrical input impedance, electroacoustical transfer function, resonance frequency and quality factor are investigated. Thermal analysis of designed transducer is performed in finite element analysis. Measured results of the transducer are compared with the theoretical results.