In this chapter we present our published research results concerning the use of phosphonates and phosphonic acids synthesized in our laboratory as corrosion inhibitors. Firstly, the corresponding synthetic pathways used to prepare this type of inhibitors have been illustrated. Also, the different experimental methods used to evaluate the inhibition activities of these derivatives have been presented in this chapter such as weight loss measurements, polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), atomic force microscopy (AFM), etc. On the other hand, the theoretical approaches such as Density Functional Theory (DFT) and Molecular Dynamic Simulations (MDS) are also implanted in this chapter in order to determine correlations between the experimental efficiencies and some calculated structural and electronic properties.