The Li3-xCoxN (x = 0.2-0.6) system was investigated for use as an anode material for lithium rechargeable cells. The anode performance of this system was evaluated by using Li metal/Li3-xCoxN cells. Li2.6Co0.4N in this system exhibits the highest specific capacity of 760 mAh/g in the 0-1.4 V range, and shows the best cycle performance. The capacity of the first extraction was 2-x Li/mol, and depended on the amount (x) of substituted Co. In addition, the structure changed gradually from the crystalline phase with hexagonal symmetry to the amorphous phase as lithium was removed during the first extraction. The cycle performance of a lithium-ion cell was evaluated by using the Li1.6Co0.4N/LiNiO2 cell. This cell showed good cycleability of more than 240 cycles. This system is thus very promising for application to lithium-ion cells.