Multi-walled carbon nanotubes (MWCNTs) were decorated with cobalt nanoparticles (Co-NPs) by a simple thermal decomposition method. The prepared nanohybrid material (nanoCo-MWCNTs) was then cast on the surface of a glassy carbon electrode (GCE) as a novel electrocatalyst for the construction of a sensitive electrochemiluminescence (ECL) sensor. The fabricated sensor (GCE/nanoCo-MWCNTs/Nafion) showed excellent electrocatalytic activity toward luminol and H2O2 oxidation reactions at neutral media. Under optimal experimental conditions, the ECL signal intensity of the sensor was linear with the concentration of luminol in the range between 80 nM and 140 M (r = 0.9963) and also with the concentration of H2O2 in the range between 1 nM and 240 mu M (r = 0.9980). Detection limits (S/N = 3) for luminol and H2O2 were 8.7 and 0.2 nM, respectively. The relative standard deviations (RSD) for repetitive measurements of 100 M luminol (n = 10) and 10 mu M H2O2 (n = 11) were 1.6% and 2.0%, respectively. Also, the prepared sensor was further modified with glucose oxidase (GOx) to fabricate a glucose ECL based biosensor (GCE/nanoCo-MWCNTs/GOx/Nafion). The fabricated ECL biosensor exhibited excellent performance toward glucose detection in the concentration range between 05 and 600 M with a satisfactory detection limit (50 nM) and reproducibility (23%). (C) 2015 Elsevier B.V. All rights reserved.