The study on n-ZnO/rGO composites for H2S concentrations ranging from 2 ppm to 100 ppm has led to the development of a precise theoretical model to describe the complex conductivity σ*(ω) over a wide frequency range. From 1 Hz to 1.109 Hz. Consequently. This method allowed to identify a distinct Cole-Cole type relaxation in the extended frequency domain and further. To derive and study some fundamental parameters of this relaxation characteristics such as relaxation time. Ionic strength and low and high frequency conductivity values. To extract these grain boundary properties from the complex conductivity σ*(ω) behavior of n-ZnO/rGO composites. A model of an equivalence electric circuit was used. This approach was selected because of its ability to reflect the conduction properties of the composites and more generally the inter-grain and inter-grain boundaries interactions and to only a lower extent the frequency dependences of conduction. The data collected has depicted a notable variation in conductance at an optimum concentration of 30 ppm that affects the conduction properties of gas sensors. These findings shed light on conduction mechanisms in gas sensors and have potential applications in enhancing environmental monitoring technologies.