A study has been carried out on the influence of extrusion and drawing related process parameters with an object of obtaining high modulus poly ether ether ketone yarns that can be tailor made to meet critical requirements of aerospace applications. The influence of the interaction between rheological properties, spinning process variables, and drawing conditions has been given special attention to engineer a yarn that exhibit excellent structure property relationships. The wide angle X-ray diffraction results suggest that drawing carried out above glass transition temperature (T-g) influences the structure that include unit cell parameters, density, and mechanical properties. The degree of orientation characterized in terms of sonic velocity measured as high as 3 km/s with sonic modulus of 105 gpd. With progressive increase in draw temperature, crystallinity was found to increase, and useful properties were observed at an optimum draw temperature of 200 degrees C (may be region of maximum crystallization rate) primarily attributed to the maximum crystallization temperature and the heat setting effect. Thermal studies (TGA) indicate that these materials can be used in high temperature applications (up to 250 degrees C) for long time exposure and 500 degrees C for short term exposure. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112:2497-2510, 2009