Li[Li1/3Ti5/3]O-4 having a defect spinel-framework structure (Fd ($) over bar 3m; a = 8.36 Angstrom) was prepared and examined in nonaqueous lithium cells. Li[Li1/3Ti5/3]O-4(white in color) was reduced to Li-2[Li1/3Ti5/3]O-4 (dark blue) at a voltage of 1.55 V and the reaction was highly reversible, X-ray diffraction measurements indicated that the lattice dimension aid not change during the reaction [GRAPHICS] Since the reaction consists of lithium ion and electron insertion into/extraction from the solid matrix without a noticeable change in lattice dimension, called a zero-strain insertion reaction, capacity failure due to the damage to the solid matrix was not observed even after 100 cycles. Feasibility of zero-strain insertion materials for advanced batteries is discussed based on the experimental results.