In this work, we report the dielectric properties of Single wall Carbon Nanotubes (SWCNTs)-based phantom that is mainly composed of gelatin and water. The fabricated gelatin-based phantom with desired dielectric properties was fabricated and doped with different concentrations of SWCNTs (e.g., 0%, 0.05%, 0.10%, 0.15%, 0.2%, 0.4% and 0.6%). The dielectric constants (real ε′ and imaginary ε′′) were measured at different positions for each sample as a function of frequency (0.5–20GHz) and concentrations of SWCNTs and their averages were found. The Cole–Cole plot (ε′ versus ε′′) was obtained for each concentration of SWCNTs and was used to obtain the static dielectric constant εs, the dielectric constant at the high limit of frequency ε∞ and the average relaxation time τ. The measurements showed that the fabricated samples are in good homogeneity and the SWCNTs are dispersed well in the samples as an acceptable standard deviation is achieved. The study showed a linear increase in the static dielectric constant εs and invariance of the average relaxation time τ and the value of ε∞ at room temperature for the investigated concentrations of SWCNTs.