The current study presents a one-step solid-state in-situ thermal polymerization approach to prepare silicon nanoparticles-polyethylenedioxythiophene (SiNPs-PEDOT) nanocomposites. The structure-related electrochemical performance of the in-situ polymerized 2,5-dibromo-3,4-ethylenedioxythiophene(DBEDOT) with SiNPs has been studied for the first time in application to silicon-based lithium-ion battery anodes. Thermal polymerization applied to a solution containing DBEDOT in acetonitrile with suspended silicon nanoparticles resulted in an in-situ formed SiNPs-PEDOT nanocomposite. The structure, morphology, and the corresponding electrochemical performance of the in-situ SiNPs-PEDOT nanocomposites was studied in comparison to a pure PEDOT as well as to the ex-situ polymerized SiNPs-PEDOT nanocomposites using XRD, FTIR, TGA, SEM, TEM, cyclic voltammetry, impedance spectroscopy, and constant current charge-discharge cycles. The XRD, FTIR, and TGA analysis reveal that the in-situ polymerization of monomer is not impeded by the presence of the silicon nanoparticles. The SEMand TEM studies reveal a uniform dispersion of SiNPs within in-situ polymerized PEDOT matrix compared to ex-situ formed SiNPs-PEDOT nanocomposite. In the lithium-ion battery anode, the in-situ polymerized SiNPs-PEDOT nanocomposite demonstrates the enhanced lithiation-delithiation kinetics, conductivity, and rate capability in comparison to the ex-situ SiNPs-PEDOT nanocomposite. (C) 2016 Elsevier Ltd. All rights reserved.