The present work aims to investigate the in-situ decomposition behavior of sintered Ti3GeC2 MAX phase. The samples were heated to temperatures ranging between 1623 and 1773 K in air and held isothermally for 120 min. Thermogravimetric analysis yielded a weight loss of upto 30% in the temperature range 1683–1698 K, attributed to evaporation of the GeO2 phase. The decomposition rate was parabolic in nature for temperatures ≥ 1723 K; at lower temperatures it was near-parabolic. The rate of decomposition was analyzed using conventional kinetic models and the activation energy for decomposition was dependent on several physical and chemical factors. Decomposition was found to initiate with an activation energy of about 504 kJmol−1. The major phase after complete decomposition was rutile having a layered microstructure with trace amounts of GeO2. © 2020 Elsevier B.V.