A new potentiometric sensor, namely, Pt vertical bar Hg vertical bar Hg-2 FUM vertical bar graphite, where FUM represents the fumarate ion was developed for the measurement of fumaric acid in foods. The characteristics, performance and application of the technique are described. The sensitivity of the electrode to FUM was (-29.2 +/- 0.6) mV decade(-1) over a wide concentration range (7.5 x 10(-7)-1.0 x 10(-2) mol L-1), at pHs between 6.0 and 9.0, and the detection limit was 5.8 x 10(-7) mol L-1. The electrode is easily constructed at a relatively low cost, has a fast response time (within 15-30 s) and can be used for up to 5 months without showing any significant changes in performance. The sensor displayed good selectivity in the presence of a variety of other anions (carboxylates and inorganic anions). It was successfully used for the determination of fumaric acid in powdered food products including gelatin dessert powders, instant pudding powder and ice cream powders. (C) 2012 Elsevier Ltd. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)