Glucose and lysine are important substrates involved in the Maillard reaction. The lack of studies on their electromagnetic properties has made it impossible to understand the influence of electromagnetic properties on the microwave heating process, and has hindered the application of the Maillard reaction in the microwave field. In this study, the electromagnetic properties of glucose, lysine solution and their 1 : 1 mixture were determined at frequencies of 1.7–2.6 GHz. The results show that the dielectric loss factors gradually increased. Reflection loss gradually decreased with concentration in the order of glucose > mixture > lysine. The heating rates gradually increased at low concentrations (≤5%) and slowly changed at high concentrations (≥10%). These results indicate that the effect of electromagnetic properties on the heating rate is related to concentration. The heating rates depended on the dielectric properties at low concentrations (≤5%), whereas microwave-absorption properties dominated at high concentrations (≥10%).