Conducting polypyrrole-nickel oxide (polypyrrole-NiO) composites were synthesized by in situ deposition technique by placing different weight percentages of NiO powder (10, 20, 30, 40, and 50%) during the polymerisation of pyrrole. The polypyrrole-NiO composites were later characterised with Fourier transform infrared spectroscopy (FTIR) which confirms the presence of polypyrrole in the composite. AC conductivity was studied in the frequency range from 102 to 107？Hz. From these studies it is found that AC conductivity remains constant at low frequency and increases rapidly at higher frequency, which is the characteristic behavior of disordered materials. The dielectric behavior of these composites was also investigated in the frequency range 102–107？Hz. It is observed from these studies that the dielectric constant and dielectric tangent loss decrease exponentially with frequency. The composites exhibit a low value of dielectric loss at higher frequency. 1. Introduction Polymers have been considered as insulators as they found many applications due to their insulating properties. So far, any electrical conduction in polymers which is generally due to loosely bounded ions was mostly regarded as an undesirable phenomenon [1]. However, emerging as one of the most important materials in the twentieth century, the use of polymers moves from primarily passive materials such as coatings and containers to active materials with useful electronic, optical, energy storage, and mechanical properties. Although conducting polymers are known as new materials in terms of their properties, the first work describing the synthesis of a conducting polymer was published in the nineteenth century. In 1862, Henry Letheby prepared polyaniline by anodic oxidation of aniline, which was conductive, and showed electrochromic behavior. For more than three decades, conjugated organic polymers were known as the best candidates because of their unique electrical transport properties as well as their potential utility in the emerging technology [2, 3]. Electrically conducting polymers are synthesized either by reduction or by oxidation reaction, which is called doping process, giving materials with electrical conductivities up to 105？S/cm. As conducting polymers exhibit significant levels of electrical conductivity, they are suitably used in electronic devices, batteries, functional electrodes, electrochromic devices, optical switching devices, sensors, and so on [4]. Among the conducting polymers, polypyrrole has drawn considerable attention due to its high conductivity, simple
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