In this study, poly(urethane)/silver (PU/Ag) composites were synthesized in dimethylformamide (DMF) with no essential extra reducing agents. The reaction medium DMF is acting as both a diluent and reducing agent for silver particles. Composites (PU/Ag) were synthesized by in situ polymerization in the existence of different amounts of silver nitrate. The formation of PU/Ag composites was approved by ultraviolet-visible (UV-vis) spectrometer, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) analyses, scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analyses, thermogravimetric analysis/differential thermal analysis (TGA-DTA), and differential scanning calorimetry. The conductivity measurements of PU and composites were done with the four-point probe technique using a Keithley 2400 electrometer. The conductivity values of the undoped PU, PU5, PU10, and PU20 were about 1.18 x 10(-7), 2.2 x 10(-6), 2.3 x 10(-7), and 1.25 x 10(-7) S cm(-1), respectively. The presence of silver particles was approved by UV-vis spectroscopy, EDX, and XRD. The formation of silver particles was determined by UV-Vis absorption spectra of the polymer matrix. According to TGA, it was observed that composites have higher thermal stability than polyurethane.