This paper reports an electroanalytical sensor developed based on reduced graphene oxide/FeNi3 (FeNi3/rGO)-ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate (HMPF6) carbon paste electrode (CPE) for determining the antioxidant additive tertbutylhydroquinone (TBHQ) in the presence of folic acid. The FeNi3/rGO synthesized by hydrothermal strategy and characterized by X-ray diffraction (XRD) and FESEM methods. The electrochemical response were found to be linearly symmetrical to TBHQ and folic acid concentrations in the range from 0.05 to 900 μM and 0.6–1100 μM with detection limits of 10.0 nM and 0.1 μM, respectively. The FeNi3/rGO/HMPF6/CPE showed high-quality for determination of TBHQ in the presence of folic acid in the real samples with the separation potential ∼600 mV. The presence study describe fabrication of novel electrochemical sensor based one carbon paste electrode modified with reduced graphene oxide/FeNi3-ionic liquid nanocomposite as sensor for simultaneous determination of tert-butylhydroquinone and folic acid. Display omitted •Reduced graphene oxide/FeNi3-ionic liquid as novel electro-catalysts.•The first electrochemical sensor for simultaneous determination of tert-butylhydroquinone and folic acid in food samples.•Nano-molar determination of tert-butylhydroquinone in food samples.