Low-cost, uniform, and monodisperse spherical particles are desirable for a variety of applications. We report the realization of uniform spherical magnesium oxide with a diameter of 10.5 mu m and specific surface area of 140.9 m(2) g(-1) resulting from a facile seed-induced precipitation in the presence of a trace amount of phosphate species. By optimizing the experimental parameters, the results demonstrate that the morphologies of magnesium oxide precursors are very sensitive to the amount and the sequence of addition of Mg-5(CO3)(4)(OH)(2) . 4H(2)O seeds, as well as the amount and type of phosphate species. These particles have also been used as a packing material for high performance liquid chromatography. In comparison with the commercial spherical silica, as-synthesized spherical magnesium oxide exhibits excellent efficiency in the separation of polycyclic aromatic hydrocarbons, and has a larger retention to planar compounds in contrast to non-planar ones. It is believed that this method will provide a simple and versatile approach to large-scale production of spherical magnesium oxide via a facile seed-induced mechanism. ne spherical magnesium oxide may find widespread use as a packing material in the group separation of polycylic aromatic hydrocarbons from target samples.