Abstract: Synthesis process for new particles of Li4Ti5O12, Li(4−&agr;)Z&agr;Ti5O12 or Li4Z&bgr;Ti(5−&bgr;)O12, preferably having a spinel structure, wherein &bgr; is greater than 0 and less than or equal to 0.5 (preferably having a spinel structure), &agr; representing a number greater than zero and less than or equal to 0.33, Z representing a source of at least one metal, preferably chosen from the group made up of Mg, Nb, Al, Zr, Ni, Co. These particles coated with a layer of carbon notably exhibit electrochemical properties that are particularly interesting as components of anodes and/or cathodes in electrochemical generators.