The electroactive materials LiFePO4 and LiFe0.9Mg0.1PO4 have been synthesized by a novel carbothermal reduction (CTR) method. The transition metal reduction and lithium incorporation processes are each facilitated by the high temperature carbothermal reaction based on the C-->CO transition. These CTR conditions favor stabilization of the iron as Fe2+ as well as offering some control of the product morphology and conductivity. Electrochemical evaluation of the CTR LiFe0.9Mg0.1PO4 reveals a lithium insertion plateau around 3.4 V vs. Li together with a specific capacity of over 150 mAh/g. Differential capacity data confirm the two-phase nature of the insertion reactions as well as the outstanding ionic reversibility. Few technical obstacles have been encountered in scaling the CTR process from a laboratory process to that required for pilot production. (C) 2003 The Electrochemical Society.