Synthesis of Li1+x Ni0.5Mn0.5O2+δ (x =0, 0.3) cathode materials for secondary lithium batteries was performed by freeze-drying method using various chemical precursors. Electrochemical performance of materials demonstrates considerable dependence on their chemical prehistory and Li stoichiometry. Increase in duration of the final annealing at 900°C since 1–12h results in decreasing capacity values for all x and chemical prehistories. Observed capacity fall is explained by smaller grain size and, therefore, shorter Li diffusion pathways in the samples obtained using short time annealing.