In situ polyaniline (PANI) films were grown from an aqueous hydrochloric acid solution on glass substrates via the chemical oxidation of aniline using hydrated ferric chloride, FeCl3.6H2O (FC). The effect of initial molar ratios of FC/aniline on the yield of PANI films was monitored using the quartz crystal microbalance technique. The morphology of the resultant polymer film and powder was examined using scanning electron microscopy. It was found that the film possesses a porous character; however, the polymer powder consists of small particles with interconnected nanofibers. The polymer powder formed in the bulk was characterized using the energy dispersive analysis of X-ray, the X-ray diffraction, and the thermal gravimetric analysis. A comparison between the PANI produced from FC and ammonium peroxydisulfate was considered and discussed. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012