Natural materials, especially derived from medicinal plant extracts, which are renewable, biodegradable, and highly effective, have been the core subject of research lately due to the growing demand for sustainable and environmentally benign corrosion inhibitors. This dissertation explores the corrosion inhibition potential of Sclerocarya birrea (Anacardiaceae .Rich) Hochst. subsp. caffra (marula) leaf extract for mild steel, API X42 pipeline steel and Aluminium (AA 1100) alloy in 3.5 % NaCl and 1 M H2SO4 corrosive environments. These materials are often utilized in petrochemical, water transportation and construction industries where these corrosive environments are prevalent. Initially, we used FTIR, UV-Vis, and GC-MS techniques alongside preliminary phytochemical screening to identify all the phytochemical compounds, bioactive compounds, and functional groups that will aid in suppressing corrosion. The mechanisms and effectiveness of the Sclerocarya birrea ethanolic extract inhibitor were assessed by a multifaceted approach expending weight loss analysis, thermodynamics and adsorption studies, electrochemical impedance spectroscopy (EIS) analysis, open circuit potential (OCP) , potentiodynamic polarisation (PDP), dense functional theory (DFT) , Monte Carlo (MC) simulations, and surface analysis such as X-ray diffraction (XRD) and Raman spectroscopic analysis. These techniques offer a thorough comprehension of the chemical interactions, adsorption processes, and inhibition efficiency that underline the leaf extract's ability to impede corrosion. When comparing the uninhibited samples to the inhibited ones, the weight loss results for the metals revealed significant corrosion for blank exposed samples in both corrosive media. As the inhibitor’s concentration increased, the inhibition efficiencies also increased, suggesting that the inhibitor's effectiveness was dose dependent. Sclerocarya birrea inhibitor served as a mixed-type inhibitor, lowering both anodic and cathodic processes on the metal surface, according to electrochemical investigations such as EIS and PDP. With increasing inhibitor concentration, EIS measurements indicated a decline in double-layer capacitance (Cdl) and an increase in charge transfer resistance (Rct) , demonstrating the inhibitor's ability to generate a protective barrier. Stable potential values during prolonged exposure periods demonstrated that a stable protective film has been formed on the metal surface, as confirmed by OCP measurements. Thermodynamic parameters determined by adsorption isotherms indicated that physisorption is the dominant adsorption mechanism of the inhibitors on the metal surfaces. The best fit in both 3.5 % NaCl and 1 M H2SO4 corrosive solutions is given by both the Langmuir and Temkin adsorption isotherm models, which suggests a monolayer adsorption mechanism. With values compatible with physisorption interactions rather than chemisorption, the computed Gibbs free (ΔG) energy of adsorption validates the inherent spontaneity of the adsorption process. The molecular interactions between the active ingredients in the inhibitor and metal surfaces were further explained by computational insights from DFT and Monte Carlo simulations. DFT simulations determined which functional groups in the leaf extract were responsible for adsorption; they revealed that some of these groups had a high capacity to donate electrons, which made it easier for them to interact with the metal surface. By visualizing the arrangement of extract molecules on the metal surface, simulating the adsorption process, and quantifying adsorption energy values that supported the experimental results, Monte Carlo simulations enhanced these findings. Additional layers of verification were offered by structural and spectroscopic examinations from Raman spectroscopy and XRD surface analysis. The inhibitor's significance for surface protection rather than bulk alloy change is confirmed by XRD data obtained, which also confirms that the crystalline structure of inhibited metal samples is substantially intact. Shifts in distinctive peaks linked to the mild steel, API 5L X42 pipeline steel and AA 1100 metal surfaces were revealed by Raman spectroscopy, signifying the development of a thin protective organic layer. The development of a physiosorbed layer and the involvement of functional groups from the inhibitor, such as C-H, C=C, OH, and C-O, in the inhibitory process were further complemented by changes in Raman spectrum characteristics. Overall, the results obtained from this investigative study demonstrated that Sclerocarya birrea ethanol extracted leaf extract exhibits outstanding inhibitory efficacy in both acidic (1 M H2SO4 ) and simulated seawater (3.5 % NaCl) environments, proving its potential as a mild steel, API X42 pipeline steel and aluminium (AA 1100) potential inhibitor that is both economical and sustainable. This study adds to the expanding corpus of research on plant-based corrosion inhibitors by shedding light on the structural effects, thermodynamic behavior, and molecular interactions of natural inhibitors on different metals. The findings imply that Sclerocarya birrea inhibitor’s eco-friendliness and effectiveness in combating corrosion render it a strong contender for substituting synthetic inhibitors, which are frequently linked to human health and the environment threats. The significance of multidisciplinary approaches in corrosion science is emphasized in this dissertation, which merges computational modelling and experimental approaches to clarify the complex dynamics of corrosion inhibition and advance the creation of sustainable materials that can be adopted for industrial use.