In this work, we describe our efforts to produce Mn₃O₄–graphene nanocomposites based on a convenient andfeasible solution based synthetic route under mild conditions. According to transmission electron microscopy (TEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) results porous Mn₃O₄ nanocrystals (NCs), 20–40 nm in size, are uniformly deposited on both sides of the graphene nanosheet (GNS) matrix. Significantly, the as-prepared Mn₃O₄–graphene nanocomposites exhibit remarkable pseudocapacitive activity including high specific capacitance (236.7 F g^–1 at 1 A g^–1), good rate capability (133 F g^–1 at 8 A g^–1), and excellent cyclability (the specific capacitance only decreases by 6.32 % of the initial capacitance after 1000 cycles). The excellent pseudocapacitive performance of the Mn₃O₄–graphene nanocomposites electrode is probably due to the positive synergistic effects between the Mn₃O₄ and GNS. Namely, the intimate combination of the conductive graphene network with uniformly dispersed porous Mn₃O₄ NCs not only greatly improves the electrochemical utilization of Mn₃O₄, but also increases the double-layer capacitance of the graphene sheets. These characteristics make this nanocomposite a very promising electrode material for high performance supercapacitors.