A 10-arm –NH2 terminated polyamidoamine (PAMAM) dendrimer with a diethylenetriamine core and a redox centre is synthesized using a new protocol. This dendrimer is further used to produce dendrimer-functionalized magnetic nanoparticles (Fe3O4@D-NH2), which are potential electrode and supercapacitor materials for electrochemical supercapacitors. The electron charge transfer mechanism between the core and the branched surface of the dendrimers is ideal for energy storage. Iron oxide nanoparticles with high specific surface area and porosity are looked upon as electrochemically active materials. Combining the advantages from both dendrimers and iron oxide nanoparticles, porous Fe3O4@D-NH2 is of considerable interest due to its large surface area, unique porous structure, diversified composition and excellent electronic conductivity. These extraordinary features enable Fe3O4@D-NH2 to offer high specific capacitance and charge/discharge rate which make them promising candidates as electrode material in supercapacitors, combining high-energy storage densities with high levels of power delivery. The electrochemical behavior of the material is studied by cyclic voltammetry, which shows typical rectangular I–V behavior of an ideal supercapacitor. With a high surface area, the nanoparticles exhibits high charge storage and delivery capabilities possessing optimum capacitance value in the range of 70–120 F/g depending on material loadings in various electrolytes.