Dielectric parameters (i.e. permittivity) are fundamental to the simulation, design, modeling, and developing of microwave applications. For targeted objects, the complex permittivity is an essential parameter that affects its characteristics of scattering and microwave radiation. Thus, in microwave remote sensing applications, the knowledge of the dielectric property of vegetable materials is used not only to detect planting areas for monitoring and to able to specify the growth stage of them in seasonal variations, but also to determine the water requirement of the plant for controlling (water stress). This paper focuses on determining the dielectric parameters of orange and lemon leaves, grown in the Mediterranean coasts of Turkey, depending on the moisture content (MC) and frequency by measuring the samples (leaves) with waveguide transmission line technique in the larger part of the C band frequency range (4.90-7.05 GHz) (compatible with WR159) in order to propose a novel model based on curve fitting method for estimating the real part of dielectric constant ( ϵ ′ ) and the imaginary part of dielectric constant ( ϵ ′′ ). Using dielectric measurement results of orange leaves, our model based on frequency and MC is compared with the dielectric measurement results of the lemon leaves, which is in the same family with orange species, to specify the accuracy of the proposed model. The determination coefficient, R 2 , and mean square root of errors values are also obtained as 0.966 and 0.824, respectively.