In this paper, magnesium based materials (Mg and Mg-alloy (AZ91D)) were surface modified using various organic acids (carboxylic and phosphonic), in order to improve corrosion resistance and enhance theirs biocompatibility. Formations of surface layer were performed by tethering by aggregation and growth (T-BAG) method. Organization and bond mode of these layers were examined by Fourier transform infrared spectroscopy (FTIR). Additionally, semiempirical quantum molecular modeling calculation methods were used for getting insight into their structural and electronic properties, as also as corrosion resistance in the physiological solution (Hanks' solution). Corrosion resistance of modified materials were investigated by electrochemical impedance spectroscopy (EIS) in the physiological solution (Hanks' solution) and obtained results reveal a beneficial effect of the modification by forming organic acids self-assembled monolayer (SAM) on the corrosion properties of magnesium based materials, especially layers of octadecylphosphonic acid. The maximum corrosion inhibition efficiency of 87% for magnesium and of 93% for Mg-alloy (AZ91D) are achieved by the formation of octadecylphosphonic acid (ODPA) SAM.