A process for producing a
lithium-containing
composite oxide having a large volume capacity density, high safety, excellent durability for charge /
discharge cycles, and further, excellent low temperature characteristics, which is suitable for
mass production, is provided.A process for producing a
lithium-containing
composite oxide represented by a general formula LipNxMyOzFa (wherein N is at least one type of element selected from the group consisting of Co, Mn and Ni, M is at least one type of element selected from the group consisting of Al, an alkali earth
metal element and a
transition metal element other than N, 0.9≦p≦1.2, 0.97≦x≦1.00, 0<y≦0.03, 1.9≦z≦2.2, x+y=1 and 0≦a≦0.02), the process comprising a step of firing a blended product containing a
lithium source, an N element source, an M element source and, as the case requires, a
fluorine source in an
oxygen-containing
atmosphere;wherein as the N element source and the M element source, a product produced by impregnating a solution containing the M element source into a
powder containing the N element source and
drying them, is employed, and as the above firing, a first-stage firing at from 250 to 700° C. is applied and a second-stage firing at from 850 to 1,100° C. is subsequently applied to the fired product of the first-stage firing.