In this paper, we report a new and convenient synthetic method based on a reaction in an aqueous system, which can produce a new nanocomposite superionic system (CdHgI4/HgI2) at 70 degrees C for 20 min. It is the first time that these nanocomposites are synthesized. In this work, we have chosen lithium iodide, cadmium and mercury acetate as starting reagents. First, an aqueous solution of cadmium acetate, surfactant and lithium iodide is obtained. Second, an aqueous solution of mercury acetate and lithium iodide is prepared. Then obtained solution is added to the first solution. The effects of the surfactant and mole ratio of Cd: Hg have been optimized to achieve the best products on morphology and purity. When the molar ratio of Cd: Hg is 1: 1, in the absence of surfactant also in the presence of CTAB and Triplex, pure aggregated nanostructures are formed. The nanocomposites are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X- ray diffraction (XRD) and cyclic voltammetry (CV). The electrical conductivity measurement carries out at frequencies of 100 Hz, 1000 Hz, 10 kHz and 100 kHz in the temperature range 70- 140 degrees C. Results show that the best morphology and purity have been achieved in the absence of surfactant, in 1: 1 ratio of precursors. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.