Morphology and size of poly(m-phenylenediamine) (PmPD) can be tuned readily with conventional chemical oxidation by introducing methanol (MeOH). Increasing MeOH content facilitates the formation of one-dimensional (1D) PmPD microstructures. Typically, when the MeOH content is up to 100%, 1D nanorods were formed, displaying the Ag⁺ absorbability of 2073 mg g⁻¹.