AKZO NOBEL has developed a new rigid-rod polymer fibre called M5. This new fibre offers high (specific) tensile and compressive mechanical properties, good adhesive bonding with common thermosetting resins, good chemical resistance and a broad useful temperature range up to 600 degrees C. Advanced LightWeight Engineering, in co-operation with the Structures and Materials Laboratory, Faculty of Aerospace Engineering, Delft University of Technology, executes research on composites with this new fibre as reinforcement. The main goals of the research are to establish mechanical properties of M5 composites and to identify attractive applications for M5 composites. This research led to the following conclusions. M5 outclasses most other engineering fibres and its compressive strength must be considered high for a polymeric fibre, with values as high as 1750 MPa derived from three-point bending tests. M5 is suited for use in special products, for which carbon fibres cannot be used, or where the application of M5 offers a significant advantage. Examples of such products are: LPG tanks, drive shafts, Side Impact Protection Beams for cars and Fibre Metal Laminates. M5 can also be used in any other product currently made with carbon fibre composites, except those which exploit the electrical and/or thermal conductivity of carbon fibres.