We report a facile, two-step synthesis process for a porous polyaniline/reduced graphene oxide composite (PANI/rGO-HT) that involves the oxidative polymerization of aniline, followed by the hydrothermal treatment of polyaniline (PANI) and graphene oxide. The reduction of graphene oxide under hydrothermal conditions in the presence of PANI nanoparticles yields a three-dimensional porous composite with a specific surface area of 228 m2 g−1, which delivers high specific capacitances from 420 to 239 F g−1 at current densities of 0.2–20 A g−1. PANI/rGO-HT exhibits remarkable electrochemical stability due to the rGO, achieving a capacitance retention of 80% after 6000 cycles at a high current density of 2 A g−1, which unveils its promising potential for supercapacitor applications.