Some new pyridinium bromide derivatives inhibitors, namely;1-benzyl-4-{N-[(4-hydroxyphenyl) methylidene] hydrazinecarbonyl)pyridine-1-ium bromide, A1; 1-benzyl-4-{N-[(4-ethoxyphenyl)methylidene]hydrazine carbonyl}pyridine-1-ium bromide, A2; 1-benzyl-4-{N-[(4-propoxyphenyl) methylidene] hydrazinecarbo-nyl}pyridine-1-ium bromide, A3; were synthesized and studied as inhibitors corrosion for meld steel in 1M H2SO4solution at room temperature via loss of weight measure ementsfor 24 hours. The results showed that inhibition for all pyridineumbromide derivatives have high values with the high concentrate. Increase in inhibition concentrate with corrosion rate decreases, inhibitor increasing and surface coverage degree increases. The free energy value of revealed physisorption effects for (A1, A2, and A3) and gave useful information to predict the interaction nature between the surface of metal and the organic molecules as corrosion inhibitors.