The Ge-containing polymers (e.g. C6H10Ge2O7) used as additives to superconducting MgB2 in the ex-situ spark plasma sintering route, significantly enhance the critical current density Jc in high magnetic fields [1, 2]. Investigation and understanding of the decomposition processes of Gebased polymers in the presence or not of MgB2 deserves attention for pinning control and optimization. In this work are presented results of thermal analysis on another polymer from the same family of Ge-polymers. Namely, thermodynamic transitions during heating and cooling of the GeSP (also noted as THGP) polymer [3] under synthetic air or pure argon were revealed by differential scanning calorimetry (DSC, 20-600 °C) and thermo-gravimetric - differential thermal analysis (TGDTA, 20-1200 °C). Heating and cooling rates were of 10 °C/min. Detailed thermal analysis is supported by measurements of X-ray diffraction (XRD) and Fourier transformed infrared (FT-IR) analysis. Experiments during heating below 600 °C have shown transformation of the crystalline GeSP polymer into an amorphous state. This process is accompanied by weight loss. In Ar atmosphere, above 840 °C, only metallic Ge is detected. At higher temperatures, when heating in air, oxidation of Ge occurs, with inherent weight increase and, finally, GeO2 melts at 1115 °C.