Various electrochemical, spectroscopic, and surface techniques were utilized to examine the influence of the aqueous extract of sweet wormwood, Artemisia annua L. (AAE) on the formation of an oxide film of three types of steel (A36, 304 and 316L) and aluminum alloy (5083) in artificial seawater (ASW) in the presence of bacterium Pseudomonas aeruginosa. The research is focused on studying the structural properties of interface boundaries, electrical and dielectric properties of surface films, and electrochemical reactions at the electrodes/ASW interface boundary using electrochemical techniques of electrochemical impedance spectroscopy, potentiodynamic polarization, and cyclic voltammetry. The surface morphology of the investigated materials was examined by non-contact optical profilometry and scanning electron microscopy (SEM), while chemical analysis was performed using energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR- FTIR). The stability of the oxide film was further investigated by inductively coupled plasma optical emission spectrometry (ICP-OES). AAE was characterized using high-performance liquid chromatography (HPLC) and ATR- FTIR spectroscopy. The combination of electrochemical and surface techniques enabled the comparison of the electrochemical properties of the surface films with their structural characteristics. Based on experimental evidence the mechanism of the formation of the oxide film on alloys in the presence of bacteria was proposed, along with the mechanism of the inhibitory effect of AAE on microbiological corrosion. The oxide film formed in the presence of AAE showed improved protective properties and inhibited the Faraday processes of electrode oxidation and charge transfer between the electrode and ASW caused by the action of biofilm and chlorides on the surface film. This was attributed to the formation of a thinner oxide film, with better dielectric properties and the adsorption of phenolic acids on the charged metal surfaces through electrostatic interactions (ΔG ≈ –16.30 ± 0.80 kJ mol –1 ) that prevented microbiological activity.