In this study, a new glassy carbon electrode chemically modified with multi-walled carbon nanotubes (MWCNTs) and core-shell structured Fe3O4@[(EtO)(3)Si-L] was constructed and used.for the sensitive and selective electrochemical determination of trace amounts of citalopram (CT). New Schiff base functionalized magnetic Fe3O4 nanoparticle was prepared to use as an effective ionophore in electrochemical responses of the potentiometric sensor for the determination of CT in.aqueous solutions. The influences-of the effective parameters such as working solution pH and scan rate on the electrochemical behavior of modified electrode were investigated. This electrochemical sensor responds to CT in the wide linear range of 3.00 x 10(-7) to 1.00 x 10(-7) mol L-1. The detection limit of 532 x 10(-8) mol L-1 was obtained at pH range 3-11. The proposed sensor has a fast response time and can be applied for at least 4 months without any significant divergences in the currents. It shows simple preparation, good reproducibility (RSD = 0.73%), long-term stability (RSD = 131%), accuracy in analysis and stable electrochemical sensing of CT in the presence of a large number of vitamins, carboxylic acids, ions and drugs. (C) 2016 Elsevier B.V. All rights reserved.