Previous studies report that bi-cell piezoelectric proton exchange membrane fuel cells with a nozzle and a diffuser have been successfully developed, and this pseudo-bipolar design is expected to benefit the future development of the piezoelectric stack (PZT-Stack). In this study, an innovative PZT-Stack design composed of three L-PZT-D-type bi-cells contains a total reaction area of 24 cm(2) with a diffuser angle (theta) of 10 degrees, a channel path (L) of 5.63 mm, and a channel opening width (D) of 1 mm. To optimize the performance of the PZT-Stack, the module is investigated under various operating conditions, including the PZT vibration frequency, the cell temperature, the relative humidity in the anode, the type of electrical circuit, and the type of intake module on the anode. The stability and the performance of a PZT-Stack with a degraded membrane electrode assemblies (MEA) are analyzed. Although the degraded working mode lowers the performance of the PZT-Stack, the module is still able to function consistently and deliver positive power. The maximum net power of the PZT-Stack was 3.8627 W under a PZT frequency of 60 Hz, and a cell temperature of 50 degrees C in a parallel electrical circuit. (C) 2013 Elsevier B.V. All rights reserved.