The Li 1 + δ Mn 2 - δ O 4 samples (0.00=<δ=<0.20) were obtained by a sol-gel method and characterized using: chemical analyses, XRD, SEM, TGA, DSC, electric conductivity and thermoelectric power. The obtained results were discussed in relation to the calcination temperature, and to the results obtained on commercial LiMn 2 O 4 . The samples calcined at 300 o C (S-samples) consisting small excess of Li (δ=<0.04) showed no phase transition at 285 K and no disturbance in electric conductivity and thermoelectric power, as observed for the related samples calcined at 800 o C (H-samples). Partial thermal decomposition of the S-samples or oxygen uptake by the H-samples were observed during TGA experiments above 350 o C. The beginning of the thermal decomposition of the H-samples started at higher temperatures, depending on Li-contents. At about 920 o C, the rapid acceleration took place independently on type of the samples. The thermal decomposition up to 800 o C seems to be reversible, owing to the samples reoxidation.