The microwave absorption and reflection characteristics of composites of polypyrrole with paper, cotton cloth and polyester fabrics have been evaluated. Refiectivity measurements in the range 2–18 GHz and plane wave modelling have revealed impedance charateristics with a common transition rgion. Relationships between substrate material, polymer loading and electrical performacne have been explored. Polarisation characteristics have alos been measured. The electrical model has been successful in predicting the performance of both Salisbury screen and Jaumann multilayer designs of radar-absorbing material.