In this article, the morphologic transformation of Hibiscus sabdariffa, a natural fiber through graft copolymerization with ethyl acrylate using ceric ammonium nitrate-nitric acid initiator system, has been reported. Different reaction parameters such as temperature, time, initiator concentration, monomer concentration, and pH were optimized to get maximum graft yield (117.3%). The graft copolymer thus formed was characterized by Fourier transform infrared, scanning electron micrographs, X-ray diffraction, thermogravimetric analysis, and differential thermogravimetric analysis techniques. The graft copolymer was found to be moisture, chemical, and thermal resistant. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 448-454, 2012