Dielectric measurements on Pb2K(Nb0.1Ta0.9)(5)O-15 ceramics have been reported at 140 < T < 530 K in the 20-10(9) Hz frequency range. The tetragonal tungsten bronze-type (TTB) material shows a typical ferroelectric relaxer behaviour. Three dielectric dispersions are observed. The relaxer behaviour results from a thermally activated relaxation with a large time distribution. This relaxation could be interpreted in terms of a polar microdomain concept. The two other dielectric dispersions result from a space charge effect and from a relaxation probably related to the TTB structure.