<b>A Study of Newly Schiff Base as Corrosion Inhibitor for Metal Corrosion in Acidic Medium</b> The Schiff base 2 3,4 dihydroxy 5 nitrophenyl methylidene hydrazine 1 carbothioamide DHNPMHC synthesized by condensation of 3,4 dihydroxcy 5 nitro benzaldehyde and thiosemicarbazide. The structure of Schiff base was characterized by elemental analysis, FT IR and UV–Vis methods. The inhibition efficiency of DHNPMHC towards the corrosion of iron in 0.5M HCl was investigated using weight loss measurement technique. Results showed that DHNPMHC is an effective inhibitor for iron corrosion in 0.5M HCl solution. The inhibition efficiency also increased with concentration of inhibitor increased. The maximum corrosion inhibition e ciency of inhibitor reported at 5 5X10 5M inhibitor concentration is 89.52 . Adsorption of the inhibitor on the iron surface followed Langmuir adsorption isotherm. DHNPMHC, Corrosion, Inhibition efficiency, Iron, Weight loss measurement 1945-1950 Issue-5 Volume-5 Sanjay Kumar | Dr. Yogesh Chahar | Dr. V. K. Swami