In this study, mechanical, thermal, and morphological properties of the nanocomposites fabricated with the optimized blend of poly(ether ether ketone) (PEEK) and poly(ether sulfone) (PES) incorporated with nanobarium titanate (BT) were investigated. The optimized blend was based on the mechanical and thermal properties of the PEEK and PES in the ratio of 75 : 25 wt %. Nanoparticles were incorporated into the optimized blend with the help of twin-screw extruder. The concentration of nano-BT was varied from 2 to 6 wt % (0.411.28 vol %). With the increase in the nanosized BT concentrations, the tensile strength, tensile modulus, and elongation at break increased, whereas the crystallinity of the nanocomposites calculated by using differential scanning calorimetry method was found to decrease marginally. Morphological studies were carried out using scanning electron microscopy. The nanocomposites were evaluated by using theoretical predictive models according to Pukanszky model applicable to tensile strength and Takayanagi's model and Guth and Smallwood model applicable to tensile modulus. Upper and lower boundary of HashinShtrikman model as well as Paul's model, applicable to tensile modulus, were also used to compare the experimental data. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012