Chemically oxidation copolymerization of aniline an d o-chloroaniline with 4 molar ratios have been syn thesized using ammonium persulphate as an oxidant in HCl med ium at 0-4 0 C. The molar feed ratio of monomers is varied to prepare copolymers of different composition. The so lubility and spectroscopic analysis suggest that th e product is a copolymer of aniline and o-chloroaniline. The elect rical conductivity of the compressed pellets was me asured by two probe method. The electrical conductivity of co polymer is found to be less than polyaniline but pr ocessibility has been improved significantly in solvents like NM P, DMSO and DMF. The electrical conductivity of the copolymer is lower than polyaniline due to diminuti on in ii conjugation along the chain caused by the steric effect of the –Cl group.