The effect of a new class of corrosion inhibitor, namely, Erdosteine drug on stainless steel 304L (304L SS) corrosion was investigated as potential corrosion inhibitor in 1 M HCl solution at 25°C. Measurements were conducted utilizing “weight loss (WL), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP)" tests. From all tests, one can observe that with increasing doses of Erdosteine drug the inhibition efficacy was increased at 25°C. The adsorption of this drug on SS304L surface follows Langmuir adsorption isotherm. The inhibition efficacy increases with increasing the dose of the Erdosteine drug and decreases with rise in temperature of the medium. This drug may form a film which acts as a barrier, to minimize the contact area between 304L SS surface and HCl solution. Electrochemical results showed that this drug is efficient inhibitor for SS304L and the efficacy reached to 90 % at 300 ppm. The PP data showed that this drug acts as mixed mode mechanism. From the EIS examination, we notice the decrease in the values of double layer by increasing the dose of Erdosteine drug, on the other hand, the charge transfer resistance is increased. Thermodynamic parameters of activation and adsorption processes were calculated and discussed. The sign of the free energy of adsorption showed spontaneous process of adsorption and the stability of the adsorbed film. The surface morphology of the SS304L samples was estimated utilizing “Atomic Force Microscopy (AFM), X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy (FTIR)". Results gain for all tests used are in good agreement. To study the stability of Erdosteine and its interaction with solvent at different time intervals, different solvation thermodynamic parameters were determined from; density, refractive index and UV-spectra measurements.