The analysis of hydrogen gas ingress during the corrosion of stainless steel in pickling acid such as 2N H2SO4 in the presence and absence of an ecofriendly inhibitor Thiamphenicol[TPC] has been carriedout using mass loss, gasometric and electrochemical studies. The antibiotic seems to be more effective in plummeting the dissolution of steel in 2N H2SO4. Potentiodynamic polarization clearly indicated that the inhibitor follows mixed mode of inhibition in 2N H2SO4 medium. Hydrogen permeation and EIS measurements have confirmed that the present antibiotic checks the dissolution of SS 304 efficiently in sulphuric acid. The theoretical values of EHOMO, ELUMO, ∆E and dipole moment in the presence of inhibitor established its effective adsorption on SS 304 metal surface. © 2017 University of Manchester and the authors.