AbstractDielectric relaxation measurements on aqueous solutions of alanine and phenylalanine were carried out using time domain reflectometry (TDR) at 25, 30, 35, and 40 °C in the frequency range from 10 MHz to 20 GHz. Aqueous solutions of alanine and phenylalanine are prepared for five different molar concentrations of the respective amino acid. For all the solutions considered, only one relaxation peak was observed in this frequency range. The relaxation peaks shift to lower frequency with an increase in alanine and phenylalanine molar concentration. The molar enthalpy of activation and molar entropy of activation show endothermic interactions