Composed based on pyrogallol and formaldehyde (PF) reached by NiO nanoparticles has been prepared using sol-gel method to obtain negatronic PF/Ni devices. The obtained materials were subjected to heat treatment under inert atmosphere at 650 degrees C for 2 h. The X-ray diffraction analysis (XRD) shows that PF sample was composed of amorphous material while PF/Ni XRD spectra exhibited the presence of metallicnickel characteristic lines. The transmission electron microscopy (TEM) images indicate that PF sample was formed by homogenous material, and metallic nickel nanoparticles sized around 30 nm were dispersed in the PF/Ni nanocomposite. dc I(V) characteristics indicate a symmetric and non-linear behavior and the presence of negative differential resistance (RDN) phase in the PF/Ni sample. The dc conductivity (sigma(dc)) can be explained by Variable Range Hopping (3D-VRH) conduction model in both samples. The ac conductance shows the dominance of hopping conduction mechanism in PF sample; however, the Correlated Barrier Hopping (CBH) model seems to be dominant in the PF/Ni nanocomposite. The Nyquist plotswere used to identify an equivalent circuit with the aim to study the possible contribution of the grainsand boundary grains to the samples conductivities. (C) 2014 Published by Elsevier B.V.