The electrochemical behavior of nanopolyaniline (nPANI) particles dispersed as a stable phase in HCl and H2SO4 solutions on a gold electrode was studied and compared using cyclic voltammetry (CV) and chronoamperometry methods. The electrochemical results showed two irreversible-redox conversions within the polyaniline structure which are controlled by the adsorption and diffusion mechanism of nPANI particles. The total numbers of redox active sites per nPANI particle were determined using CV and chronoamperometry methods. The Langmuir adsorption isotherm was used to describe the adsorption process, and the corresponding adsorption parameters (θ max and ΔG ads) were calculated. The quantum chemical calculations and Monte Carlo simulation demonstrated that polyaniline as a macro molecule enables to replace water and acid molecules from the surface upon its adsorption to the gold substrate. The surface analysis of the electrode using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy demonstrated the adsorption of nPANI particles. Moreover, both experimental and simulation results confirmed that the adsorption of nPANI-HCl particles is higher than nPANI-H2SO4 particles.