Reduced graphene oxide (rGO) obtained from aqueous graphene oxide (GO) tends to agglomerate with time and hinders the commercial scale applications for high-density energy storage. Here, we report a photo-catalytic reduction of GO dispersions in N-Methyl-2-Pyrrolidone (NMP) under deep UV light (λ ~ 253 nm) for 60 min. The obtained hydrophobic rGO dispersions are electrochemically stable for more than 160 d and exhibit a high Brunauer–Emmet–Teller (BET) surface area of ~260 m2 g−1. The NMP being a dipolar aprotic solvent serves as an electron donor and its high dipole moment enhances the electrochemical stability of rGO. Furthermore, the fabricated supercapacitor exhibits a high specific capacitance, charge retention, energy and power density of ~220 F g−1 (current density of 0.5 A g−1), up to 1000 charging/discharging cycles, 7.32 Wh kg−1 and 130 W kg−1, respectively. The high stability of dispersion and electrochemical performance of synthesized rGO is envisaged for potential applications in high density energy storage and conductive inks for flexible electronics.