The polyoxometalate [PMo11O39](7-) was synthesized and used as catalyst for the reduction of nitrite ions. This mono-lacunary keggin anion, cited, as PMo11, was confined within a matrix of either oxidized single walled carbon nanotubes (ox-SWCNTs) or reduced graphene oxide (rGO) on glassy carbon (GC) electrodes to improve the electron transfers. Five different configurations were characterized using cyclic voltammetry and evaluated in an amperometric sensor setup for nitrite detection where the amount of the different components were optimized. The configuration using only ox-SWCNTs and PMo11 on GCE showed best sensitivities of up to 44.41 mA Lmol(-1) and a satisfying reproducibility (RSD: similar to 2.64% for four identic electrodes). Furthermore, a linear range between 3.0 x 10(-5) mol L-1 and 1.6 x 10(-2) mol L-1 with a detection limit of 3.0 x 10(-5) mol L-1 was obtained. The final sensor setup also showed good selectivity towards interfering ions. (C) 2016 Elsevier Ltd. All rights reserved.