In this paper, novel epsilon-MnO2 microspheres with uniform flaky texture were synthesized by a precursor conversion method. Basing on this material, a novel epsilon-MnO2 microspheres/chitosan/GCE (glassy carbon electrode) electrochemical sensor prepared by a simple physical deposit method was developed for the ultrasensitive determination of Ponceau 4R. The proposed electrochemical sensor exhibits remarkable electrocatalytic activity towards Ponceau 4R, suggesting a potentially detailed reaction mechanism catalyzed by epsilon-MnO2 and demonstrating a wide linear detection range from 0.005 to 1000 mu mol dm(-3) and a low detection limit of 0.1 nmol dm(-3) (S/N = 3) for Ponceau 4R. The sensor also shows promising selectivity, stability and reproducibility and finally, is applied to determine Ponceau 4R in real samples, giving satisfactory results. (c) 2016 Elsevier Ltd. All rights reserved.