Nonisothermal crystallization kinetics and properties of poly(vinyl alcohol)/octasilane polyhedral oligomeric silsesquioxanes nanocomposite were investigated by differential scanning calorimetry and compared with pure poly(vinyl alcohol). The effects of octasilane polyhedral oligomeric silsesquioxanes content and cooling rate on the degree of crystallinity (Xc), crystallization half time (t1/2), Ozawa exponent (m), and Mo kinetics parameters were studied. The role of thermal treatment on the morphology and structure of the samples was studied by X-ray diffraction and scanning electron microscopy analyses. UV–visible analysis was used to show the polyhedral oligomeric silsesquioxanes effect on the nanocomposite structure. Electrochemical impedance spectroscopy analysis demonstrated that the best conductivity was for the nanocomposite with 1 wt% of octasilane polyhedral oligomeric silsesquioxanes.