Well-defined polyaniline (PANI) nano-objects (e.g., spheres, peanuts, rice grains, corals, and fibers) were prepared by aniline dispersion polymerization in aqueous media in the presence of various reactive polymer stabilizers (i.e., poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA), and poly[(N-vinyl pyrrolidone)-co-(vinyl alcohol)] (PNVP-co-PVA)). It was found that the shape, size, and conductivity of resulting PANI nanostructures depended on the acidic conditions along with the nature, molecular weight, and functionality of the reactive stabilizer. PANI samples were analyzed by X-ray photoelectron spectroscopy (XPS), dynamic scanning calorimetry (DSC), thermogravimetric analysis (TGA), UV-visible and FTIR spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), and conductivity measurements. PANI samples show conductivities between 5 x 10(-3) to 5 x 10(-1) S/cm depending upon the experimental conditions. The best conductivities were obtained when aniline was polymerized in a mixture of DMSO and water (2:3) in the presence of PEO- or PNVP-co-PVA-based reactive stabilizers.