High dielectric permittivity, good mechanical properties, and excellent thermal stability are highly desired for the dielectric materials used in the embedded capacitors and energy-storage devices. This study reports polyimide (PI)/barium titanate (BaTiO3) nanocomposites fabricated from electrospun PI/BaTiO3 hybrid nanofibers. The PI/BaTiO3 nanocomposites were investigated using Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscope, thermal gravimetric analysis, an electromechanical testing machine, a LCR meter and an electric breakdown strength tester. The results showed that BaTiO3 fillers were uniformly dispersed up to 50 vol% in PI matrix. The dielectric permittivity of the composite (50 vol% BaTiO3) was 29.66 with a dielectric loss of 0.009 at 1 kHz and room temperature. The dielectric permittivity showed a very small dependence on temperature (up to 150 degrees C) and frequency (100 Hz-100 kHz). The nanocomposites also showed high thermal stability and good mechanical properties. The PI/BaTiO3 nanocomposites will be a promising candidate for uses in embedded capacitors, especially in high temperature circumstance. POLYM. COMPOS., 37:794-801, 2016. (c) 2014 Society of Plastics Engineers