Poly(aniline-co-diphenylamine and 5-aminosalicylic acid), i.e., poly(aniline-co-DPA-and 5-ASA), was electrochemically synthesized in a acidic solution containing aniline, diphenylamine (DPA) and 5-aminosalicylic acid (5-ASA) in the presence of N,N-dimethylformamide (DMF), which was deposited on a reduced graphene oxide (RGO)/glassy carbon (GC) electrode to form a poly(aniline-co-DPA and 5-ASA)/RGO/GC electrode. Cyclic voltammetry demonstrated that this electrode can effectively catalyze the reduction of m-nitrophenol in aqueous solutions. Therefore, this electrode can be used to determine m-nitrophenol in aqueous media. The electrode exhibited a linear region of 20-400 mu M m-nitrophenol in a phosphate buffer solution of pH 6.5 with a correlation coefficient of 0.9955, a linear region of 20-600 mu M m-nitrophenol in a Na2SO4 solution of pH 6.0 with a correlation coefficient of 0.9997, a good repeatability and long working life. (C) 2015 Elsevier B.V. All rights reserved.