Palladium nanoparticles supported by polyaniline nanofibers were used as pre-catalysts for C-C cross-coupling reactions of aryl chlorides in water. Using regular techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) in conjunction with reactivity studies, we determined that a homogeneous mechanism is operating. The appearance of palladium nanoparticles and polyaniline nanofibers changes after each reaction accompanied by changes in the palladium oxidation state. Our methods could not rule out the contribution of a heterogeneous mechanism or indicate its extent.