Corrosion of aluminum in oxalic acid has been done by using wt-loss technique and polarization technique in presence of different concentrations of different organic derivatives of (5-Acetyl, 3-Cyano, 6-Methyl, 2-Thiopyridone, …) such as (…, 4-p Anisyl [A₁]), (…,4-p Bromo phenyl [A2]), (…, 4-p Tolyl, [A3]), (…,4-p Nitro phenyl  [A4]) and (…,4-p Chloro phenyl [A5]) at different temperatures. It is noticed from the observed thermodynamic parameters derived  from wt-loss measurements that ∆H for the adsorption of A₁, A2, A3 and A5 resulted in  a negative value (exothermic), the adsorption typed is chemical adsorption, whereas A4 acquired physical adsorption and accelerated the dissolution of aluminum. This behavior is also observed at high temperatures for A5 compound. From the polarization method studied the dissolution of aluminum in oxalic acid is decreasing as the concentration of the acid increased due to the formation of oxide passive layer (Al₂O₃. 3H₂O), the application of Evans diagram showed that the used compounds A₁, A2, A3 and A5 can act as anodic inhibitors.