In this work temperature effect on poly(ortho-anisidine), POAN, and polyaniline, PANT, nucleation and growth (NGM) mechanism was studied. Synthesis conditions using potentiodynamic method (cyclic voltammetry) at all operating temperatures were first optimized; it was found that as the system cools, the monomer oxidation potential increases. The i-t transient obtained using the potentiostatic method (potential step) was complex and its deconvolution revealed it consists of three contributions for both investigated monomers. Experimentally obtained transient deconvolution for PANT and POAN showed that initially the deposit is formed from a progressive nucleation, with hi-dimensional growth (PN2D), followed by two three-dimensional growth contributions, one controlled by diffusion (PN3Ddif) and the other by charge transfer (PN3Dct). Nuclei are the main difference between these monomers NGM since in the case of POAN the nucleation is instantaneous (IN3Dct), whereas for PANT is progressive (PN3Dct). Hence, i-t deconvolution transients recorded during ANT and OAN electro-polymerization are virtually satisfied by the same equations. It was thus concluded that both monomeric units grow through a very similar mechanism, differing mainly by the required potential and the time (rate) it takes for each contribution to appear and, with that, each type of morphology. Temperature variation does not change the respective NGM, since the contributions are the same; just their proportions and definition time of each one varies. As expected, the diffusion controlled contribution was the most affected by temperature. In short, the obtained results validated the proposed electropolymerization model, based upon the solubility of the oligomers that precipitate to originate the polymeric deposit, and enables correlating and explaining polymer morphology changes as a function of the i-t transient recorded during its electro-synthesis. (C) 2013 The Electrochemical Society. All rights reserved.