Dielectric relaxation measurements on formamide (FA) -ethanolamine (ETA) solvent mixtures have been carried out across the entire concentration range using time domain reflectometry technique at 15, 25, 35, and 45• C over the frequency range from 10 MHz to 10 GHz. The mixtures exhibit a principle dispersion of the Davidson-Cole relaxation type at microwave frequencies. Bilinear calibration method is used to obtain complex permittivity ε * (ω) from complex reflection coefficient ρ * (ω) over the frequency range 10 MHz to 10 GHz. The excess permittivity ε E , excess inverse relaxation time (1/τ ) E , Kirkwood correlation factor g eff , and thermodynamic parameters such as Gibbs energy of activation ∆G and molar enthalpy of activation ∆H are also calculated to study the solute-solvent interaction.