Fibrous composites of tetraethylortosilicate (TEOS)/polyvinylpyrrolidone (PVP) have been successfully prepared by a sol-electrospinning process and characterized by ATR-FTIR spectroscopy, and the spectroscopic features correlated with their morphology and thermal stability. PVP is a polymer with water adsorption capability and the TEOS addition allowed to increase the thermal stability of microfibers. The spectroscopic analysis of the impact of the silica-based reinforcing phase along with morphological and thermal analysis have demonstrated that TEOS in PVP/ethanol system may interfere with the evaporation of water and ethanol during ES process and with the final capacity of the material of adsorbing water. The elucidation of these mechanisms may help in the design of hybrid, organic–inorganic microfibers materials for specific applications, as adsorbent materials for heat pumps.