A highly sensitive and stable solid state electrochemiluminescence (ECL) sensor for tri-n-propylamine (TPrA, as coreactant) detection was developed using Ru(bpy)(3)(2+) ion-exchanged into the composite film of ZnO nanoparticles decorated multi-walled carbon nanotubes (nanoZnO-MWCNTs) and Nafion. The electrocatalytic activity of nano-ZnO active sites towards Ru(bpy)(3)(2+) redox reaction and also towards TPrA oxidation reaction significantly enhanced the electrochemical and ECL behaviors of Ru(bpy)(3)(2+)/TPrA system. Under optimal experimental conditions, the logarithm of ECL signal intensity of the sensor was proportional to the logarithm of TPrA concentration in the range between 5 x 10 M-11 and 4 x 10 M-4 (r = 0.9996). The detection limit (S/N = 3) for TPrA was 1 x 10 (11) M. The relative standard deviation (RSD%) for repetitive measurements (n = 41) of 100 mu M TPrA was about 4.2%. The proposed solid state ECL sensor also showed excellent reproducibility (8.1% for n = 5) and outstanding storage stability (83% of its initial ECL signal retained after 10 days). (C) 2015 Elsevier Ltd. All rights reserved.