Magnetic g-Fe2O3@SiO2 core-shell nanocomposite was prepared using Stöber method and functionalized firstly by isopropenyloxytrimethylsilane as a coupling agent to enter active acetylacetone on the surface of nanoparticles, and after that by the synthesized azo dye ligand, 2-(2-benzothiazolyl azo)-4-methoxyaniline. In such a way, g-Fe2O3@SiO2-azo dye hybrid nanocomposite was formed. The structure of the synthesized azo dye was evidenced by physical and chemical analysis using melting point, Fourier-transform infrared spectroscopy (FT-IR), CHNS elemental analysis, proton nuclear magnetic reso­nan­ce (HNMR) and gas chromatography mass spectrometry (GC-MS). The magnetic proper­ties, structure, element composition and morphology characterization of prepared mate­rials (g-Fe2O3, g-Fe2O3@SiO2, and g-Fe2O3@SiO2-azo dye) were investigated by vib­rating sample magnetometer (VSM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron spectroscopy (TEM) and field electron scanning electron micro­scopy-energy dispersive X-ray-mapping techniques. The electrochemical perfor­mance of synthe­sized g-Fe2O3, g-Fe2O3@SiO2, and g-Fe2O3@SiO2-2-(2-benzothiazolyl azo)-4-methoxy­aniline) electrodes were carried out using cyclic voltammetry (CV), galva­nostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). It was shown that the finally prepared g-Fe2O3@SiO2-2-(2-benzothiazolyl azo)-4-methoxy­aniline) hybrid nano­composite electrode possesses good storage charge capability of 580 F g-1 at 1 A g-1.