LiFe1−x Co x PO4 (0≤ x ≤1.0) solid solutions were prepared by solid-state reactions. X-ray diffraction and X-ray photoelectron spectroscopy were employed to analyze the variation of their structures and the chemical environments around the P and O atoms of the solid solution with various Co contents. The electrochemical performance of LiFe1−x Co x PO4 was also comparatively studied with cyclic voltammetry, and galvanostatic charge–discharge.