One-dimensional arrays of Co3O4 nanoparticles were obtained via the thermal treatment of cobalt oxalate nanorods, which were synthesized through a convenient solvothermal route. The optical properties of Co3O4 nanoparticles were investigated. The optical absorption spectrum indicates that the direct band gaps of Co3O4 nanoparticles are 1.52 and 2.01 eV. The galvanostatic experiment shows the excellent electrochemical performance between 3.0 and 0.2 V.