The use of short palm tree lignocellulosic fibers as a reinforcing phase in polyester and epoxy matrices has been reported. Dielectric spectra were measured in the frequency range 0.1 Hz–100 kHz and at temperature intervals from ambient to 200°C. For the polyester/palm tree, different relaxations process were identified, namely the orientation polarization imputed to the presence of water molecules in palm tree fiber and the relaxation process associated with conductivity and interfacial relaxation. In the case of epoxy/palm tree, the α mode transition associated with the glass transition of the epoxy resin, the phenomenon of conduction, and the interfacial relaxation are present. The water dipoles relaxation was not observed in this case. Dielectric measurements show that interfacial adhesion is strong for epoxy-based materials.