Thermal stability and thermomechanical behavior of a new polymer-based nanocomposite was conducted to assess the viability of its fabrication process. The nanocomposite films consisted of a polyimide matrix and dispersoids of 20nm cobalt ferrite single crystals exhibiting room-temperature coercivity of 2.9 kOe. For the sake of comparison, a bare polyimide film was also prepared. Infrared spectroscopy and x-ray diffraction analyses confirmed proper composite fabrication with development of expected phases. Dynamical mechanical analysis measurements of Tan δ and storage modulus as a function of temperature evidenced an increase in the viscous-like behavior of the composite film by incorporation of the ferrite nanocrystals within the polymeric matrix. The corresponding reduction in the storage modulus values were validated by thermo-gravimetrical analysis as a function of time and heating temperature in both, the bare polymer film and the nanocomposites.