Piezoelectric composite nanofibers based on (Na-0.5,K-0.5)NbO3 (NKN) nanoparticles embedded in poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] polymer are investigated in terms of their performance as nanogenerators. Perovskite NKN nanoparticles with similar to 30-105 nm were separately prepared by combustion synthesis using polyacrylic acid (PAA) as a fuel. Surface modification of nanoparticles by tetradecylphosphonic acid (TDPA) was essential to secure proper adhesion with the polymer in the nanofibers prepared by electrospinning. Location-dependent piezoelectricity measurements confirmed that the region of embedded NKN filler particles exhibited better piezoelectricity than the P(VDF-TrFE) matrix region. Energy harvesting performance of the flexible composite nanogenerator demonstrated similar to 0.98 V output voltage and similar to 78 nA output current, which were enhanced depending on the volume fraction of the NKN nanoparticles dispersed in the polymer. (C) 2015 Elsevier Ltd. All rights reserved.