[en] The present work is devoted to the investigation of the lithium metatantalate formation mechanism from Li₂CO₃ and Ta₂O₅ with the help of DTA, DTG, XPA, IR spectroscopy, and mass spectroscopy analysis. The main advantages of solid-phase synthesis include the possibility of obtaining a product with a definite chemical composition and a low impurity content with the use of high-purity ingredients. The results of thermographic analysis confirm a multistage process. The proposed multistage reaction mechanism of this process depends on the course of the stage processes with or without liberation of CO₂