The crystallization, morphology, micro-hardness, scratch hardness, dynamic modulus, and wear behavior of high performance poly(ether-ether-ketone) (PEEK) matrix nanocomposites reinforced with 0 to 30 wt % silicon nitride (Si3N4) nanoparticles were reported. The crystallinity of PEEK nanocomposites increases at 2.5 wt % Si3N4 but, thereafter it decreases with increasing Si3N4 content due to the hindrance to the ordering of PEEK chains. The crystallization peak temperature and crystallization onset temperature increases by 14 degrees C for 10 wt % nanocomposite. The melting temperature does not vary significantly with Si3N4 content. SEM shows almost uniform distribution of Si3N4 in the PEEK matrix. The Vickers micro-hardness and scratch hardness increases significantly up to 10 wt % Si3N4 content. The dynamic modulus of nanocomposites increases below and above T-g of PEEK. The specific wear rate of nanocomposites with 2.5 wt % Si3N4 is reduced significantly and it is lowest at 10 wt % Si3N4. However, the coefficient of friction of nanocomposites is more than that of pure PEEK. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 311-318, 2011