This short communication considers the results of developing novel glass-metal coaxial waveguide reactors. They are designed on the base of the Liebig condenser, where the central glass channel is occupied by wire. The outer shield is made of copper foil. A liquid flows between the central glass tube and the shielded outer pipe, being pumped in and out through the shielded tubes. The reactors are excited through coaxial connectors. The developed devices show moderate loss and increased penetration depth needed for smooth heating of flowing liquids. The components are studied by measurements and simulations.