Given the lack of thermodynamic data on Li_1+xM_1-xO₂ materials, LiAlO₂ was split in accordance with the principle of the group contribution method. Mathematical models for estimating the ?G^θ_f,298, ?H^θ_f,298, and C_p of LiAlO₂ were proposed on the basis of thermodynamic principles. The group contribution method was used to estimate the ?G^θ_f,298, and ?H^θ_f,298 of 56 solid inorganic compounds and the C_p,298 of 54 solid inorganic compounds to test the reliability and applicability of the model. The group contribution method was used to estimate the mathematical model of solid inorganic compounds. Results show that the experimental data selected by fitting group parameters are accurate and reliable, and the group division method is appropriate. Mathematical models for estimating the ?G^θ_f,298, ?H^θ_f,298, and C_p of three types of Li_1+xM_1-xO₂ materials were constructed on the basis of the satisfactory results. The ?G^θ_f,298, ?H^θ_f,298, and C_p,298 of the 63 common Li_1+xM_1-xO₂ materials were also estimated.