Abstract: An anodic aluminum oxide template-based process was adopted to fabricate polyaniline nanowires using the electropolymerization process. In addition, a novel template-free process was developed to synthesize the polyaniline nanofibrils using a controlled multi-potential method. The cyclic voltammetry was performed for both the nanowire and nanofibril arrays to investigate their electrochemical properties. The influences of the scan rate, different scan cycles and the micro morphologies on the cyclic voltammograms were investigated. The results show that polyaniline nanowire and nanofibril arrays present quite different cyclic voltammograms. These differences are ascribed to the various micro-morphologies and ordering state. Furthermore, a PANI nanofibril arrays based surface wave acoustic (SAW) device was fabricated utilizing the controlled multi-potential process.