In this study, the new compound of thiourea derivatives were successfully synthesized, namely N-((3chlorophenyl) carbamothioyl) benzamide (T1) and N-((4-chlorophenyl) carbamothioyl) benzamide (T2). These series of thiourea compounds were prepared from the reaction of benzoyl chloride with ammonium thiocyanate to produce benzoyl isothiocyanate, then direct reaction with amines by using condensation method. Their structures were characterized on the basis elemental analysis and spectroscopic techniques namely infrared and nuclear magnetic resonance. The Infrared spectra showed the significant results of stretching vibrations of the compounds are ν(C=O), ν(C=S) and ν(C-N) at 1533.39-1671.00 cm-1, 1256.64-1261.73 cm-1 and 1144.22-1144.81 cm-1, respectively. These compounds were investigated as corrosion inhibitors on mild steel in 1M H2SO4 using linear polarization techniques. Results show the highest inhibition efficiency of T1 is 55% while for T2 is 73%. The percentage inhibition efficiency of T2 is higher than T1 due to the difference position of substituent at meta and para.