Corrosion of mild steel and its inhibition by ceftriaxone in 1M sulfuric acid has been investigated by weight loss, open circuit potential (OCP), potential dynamic polarization and surface analysis by scanning electron microscopy SEM and electron x-ray diffraction (EDAX) techniques. Different concentration range of inhibitor solution from 10-500 ppm was used which revealed that 500 ppm solution shows excellent inhibition performance of nearly 94%. Ceftriaxone is mixed type of inhibitor but the cathodic Tafel polarization, βc values continuously increases as the concentration of inhibitor increases; hence comparatively, the cathodic polarization is more pronounce than the anodic polarization. The SEM examination shows the formation of protective surface film of inhibitor molecules on the surface of mild steel. EDAX shows peaks of N and S on the mild steel. The adsorption of inhibitor obeys the Langmuir adsorption isotherm.