The inhibition efficiency of corrosion on mild steel using acids by three different novel Semicarbazones as inhibitors have been studied using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy methods. The inhibition efficiency, corrosion rate, the nature of anchoring sites and the adsorption characteristics have been determined from the results. It was found that the newly synthesized compounds behaved as mixed type inhibitors with high inhibition efficiency. The inhibition efficiency increases with increasing the inhibitors concentration but decreases with increasing the temperature. Addition of halide ion enhances the inhibition efficiency. The adsorption of the inhibitors on the mild steel surface obey Langmuir adsorption isotherm.Scanning Electron Spectroscopy is used to examine the surface morphology of mild steel samples both in the presence and absence of inhibitors at optimum conditions. Scanning Electron Microscope reveals the formation of a smooth, dense protective layer in the presence of inhibitor.