Reduced graphene oxide (RGO)-polypyrrole nanotubes (PPyNTs) nanocomposites have been synthesized by in-dsitu chemical reduction of graphene oxide using PPyNTs as spacers. Scanning electron microscopy displays homogeneous dispersion of 1D PPyNTs onto the 2D RGO nanosheets. Significant improvement in the crystallinity of the nanocomposites with increasing RGO concentration has been confirmed from X-ray diffraction results. The investigation of thermal stability in the range of 50-690 degrees C reveals superior thermal stability of the nanocomposites compared to that of PPyNTs. Dielectric permittivity investigation exhibits enhancement in dielectric constant with RGO concentration due to interfacial polarization at the interfaces of RGO and PPyNTs. Relaxation of interfacial polarization at higher frequencies is established with a relaxation peak in the imaginary modulus formalism. The maximum ac conductivity of 1.45 x 10(-4) S/cm is achieved for 40 wt.% of RGO. Scaling of ac conductivity suggests that the conductivity relaxation process is independent of filler concentration.