Ethoxyquin (EQ) is an antioxidant widely used in the food industry. Some concerns for human health have been reported since its utilization in animal feed may lead to residues in human food such as salmon samples. This work aimed to investigate the electrochemical behavior of EQ and its major oxidation products namely a dimer of EQ (EQDM) and ethoxyquin quinone imine (EQI) by cyclic voltammetry (CV) at a carbon screen printed electrode (cSPE). The stability of these products and their reactivity against glutathione (GSH) were also studied. Oxidized products and thiol adducts were identified by a microelectrolysis of an EQ solution onto a cSPE in the absence and in the presence of GSH. The products were analyzed off‐line, by liquid chromatography coupled to a mass spectrometer (LC‐MS). One of the generated product (EQI) was shown to be highly reactive towards GSH. Based on the redox pattern of EQ, a flow injection analysis with a dual cSPE was developed in order to detect in a rapid manner EQ in salmon samples. Since matrix effects were observed, matrix‐matched calibration curves with spiked samples were built. A linear response was obtained between 20–100 μM and a limit of detection (LOD) of 7.5 μM (8.2 mg/kg of salmon). Trueness was assessed with recovery assays at three levels of concentration. The recovery was close to 100 %. Precision was determined as RSD (%) with values lower than 6 % in all cases.