Porous cobalt (Co) microspheres were successfully synthesized via a facile surfactant-free solvothermal route. These microspheres have an average diameter of about 2 µm, assembled by many primary Co nanosheets. A possible formation mechanism of porous Co microspheres is discussed. The magnetic hysteresis loop shows a ferromagnetic feature of porous Co microspheres and the saturation magnetization (Ms) and coercivity (Hc) are 115.3 J/T·kg and 6.883 kA/m, respectively.