Polyaniline (PANI) in its emeraldine base form (EB) doped with bis(2-ethylhexyl) hydrogen phosphate (also called in this article diisooctyl phosphate or DiOHP) has been investigated using UV-VIS, Raman, scanning electron microscopy (SEM), and X-ray diffraction measurements. The protonation process occurs simultaneously with plasticization of the polymer. In each process, the dopant plays a key role, and depending on the relative molar ratio of the dopant to the PANI the two processes are competitive to each other. Changes of morphology, crystallinity and spectroscopic properties of samples differing by DiOHP/PANI molar ratio and their dependence on time has been investigated.