Three-dimensional polyaniline (PANI) nanowire networks were synthesized in high yield using a "soft template" self-assembled with hexadecyltrimethylammonium bromide and oxalic acid. The PANI nanowire networks had diameters from 35-100 nm depending on synthesis conditions and/or procedures. The networks and the "cross-linking points" were clearly observed by field-emission scanning electron microscopy and transmission electron microscopy. A possible mechanism for the formation of three-dimensional PANI nanowire networks is discussed.