The Chemical synthesis of substituted derivatives of polyaniline in oxalic acid media in which an H of the aromatic ring has been replaced by an methyl and methoxy group is reported. The synthesis of substituted derivative of polaniline (PANI) such as poly (o-methoxyaniline) (POMA), poly (2,5dimethoxyaniline) (PDMA), poly (o-methylaniline) (PMLA) and poly (2,5dimethylaniline) (PDMLA) were obtained from an aqueous oxalic acid solution under chemical oxidation using ammonium per sulphate as an oxidizing agent. The resulted powder of substituted derivatives of polyaniline were characterized by UV-visible absorption spectroscopy and Fourier Transform Infra Red (FTIR) spectroscopy. It is observed that the oxidation state of polyaniline can vary depending on the group substituted in which H of the aromatic ring. The FTIR Spectrum reveals the stretching and bending vibration which clearly confirm the formation of substituted derivative of aniline.