THE CHEMICAL polymerization of diphenylamine in DMF/water (50% v/v) using sodium dichromate as oxidant and HCl as dopant is performed. The effect of monomer, oxidant, HCl concentration and temperature on both initial and overall reaction rates is investigated. The data show that both the initial and overall reaction rates increase with the increasing of monomer, oxidant and HCl concentrations in the concentration range of study. Also, both the initial and overall reaction rates increase with increasing temperature. The reaction rate law is found to be: R i = k2[monomer]0.723[oxidant]0.854[HCl]0.641 The apparent activation energy Ea is found to be 15.299 kJ/mol. Also, H* and S*, were calculated and found to be 12.67 kJ/mol and -90.184 J/mol.K, respectively.The obtained polymer sample prepared at the optimum conditions was characterized by IR, 1HMMR, TGA, DTA and electron microscopy. Also, elemental analysis was carried out to confirm the suggested structure of obtained polymer. The mechanism of the polymerization reaction was discussed.