This study aims at developing hybrid composite materials consisting of iron oxide (Fe3O4) /MXene /reduced graphene oxide (RGO) without any impurities using optimized experimental parameters to be utilized in next-generation supercapacitor applications and the searching of suitable electrolyte for the developed hybrid electrode materials. We have generated Fe3O4-decorated MXene nanosheets on RGO by a simple chemical oxidation method. The initial grain size of Fe3O4 of about 43 nm is further reduced to 30 nm when prepared with MXene nanosheets. The as-prepared samples are used as a negative electrode material and their capacitive performance is analyzed in potassium hydroxide (KOH), sodium sulphate (Na2SO4) and lithium chloride (LiC1) electrolytes. Fe3O4/MXene/RGO nanocomposites showed the best performance. Regarding the electrolytes, the following order has been obtained 5 M LiC1 > 1 M Na2SO4 > 1 M KOH, which matches well with the bare ion size order. Moreover, Fe3O4/MXene/RGO electrode exhibits an 82.1% of cyclic stability up to 5000 charge/discharge cycles at a current density of 5 A g(-1) demonstrating the best performance. (C) 2020 Elsevier Ltd. All rights reserved.