5,6-Dimethoxyindole-2-carboxylic acid has been electrochemically polymerized to form a polymer that is chemically similar to melanin, a conjugated polymer found in nature. The poly(5,6-dimethoxyindole-2-carboxylic acid) (PDMICA) films are green and electrochromic, changing color from transparent to green and then to purple as the voltage applied increases continuously from -1 to +1 V. This result is distinct from other synthetic and natural melanins, which are dark brown and have broadband adsorption that is believed to be derived from their chemical disorder. In addition, electrochemically polymerized PDMICA has a degree of crystallinity that has not been seen in melanins, as shown by 1.39, 0.32, and 0.28 nm spacings in wide-angle X-ray diffraction patterns and a nanofibrous structure, as seen in scanning electron micrographs.