Flake‐like polyaniline with various thicknesses was prepared by cationic emulsion polymerization of aniline monomer in the presence of cetyltrimethylammonium bromide (CTAB). The morphology of polyaniline with uniform and smooth flake‐like structure was observed using field‐emission scanning electron microscopy and transmission electron microscopy. The lamellar complex of (CTA)2S2O8, acting as a reactive soft template for the formation of polyaniline, was investigated using low‐angle X‐ray diffraction. The soft template provides an expanding space for the growth of polyaniline, in which the oxidization of aniline monomers can construct effectively a flake‐like structure. The concentration of CTAB plays an important role in adjusting the d‐spacing of the soft template. Crystallization and composition of polyaniline were characterized using X‐ray diffraction and Fourier transform infrared spectroscopy. The X‐ray diffraction pattern has a sharp peak at 2θ = 6.4° (d‐spacing = 13.7 Å), showing that polyaniline has a solid‐state ordering structure and high degree of crystallization. Doping and dispersive experiments were also included in the study. Copyright © 2012 Society of Chemical Industry