In the present work, we used doxycycline hyclate (DX) and tetramethylguanidine (TMG) for the synthesis of silver– silver chloride nanoparticles (DX-Ag– AgCl NPs) as a simple method for the production of nanoparticles (NPs). A new synthesis method for DX-Ag– AgCl NPs in aqueous medium, using the DX and TMG as a reducing and stabilizing agent, is reported. DX-Ag– AgCl NPs were characterized by transmission electron microscopy. The elemental composition and the crystalline nature of synthesized nanoparticles were determined by energy-dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis, respectively. From EDX, it is confirmed that synthesized NPs contain elemental silver and chloride, and their crystalline nature was confirmed by XRD. The Fourier transform infra-red spectra showed the DX present in surface of DX-Ag– AgCl NPs. Synthesized NPs analyzed for antibacterial activity by agar well method against Gram-positive and Gram-negative pathogens. Synthesized DX-Ag– AgCl NPs were spherical shaped and in the range of 10– 40 nm of size was observed from TEM images. In the crystalline nature, XRD peaks indicate the presence of silver and silver chloride in produced NPs. Synthesized NPs show potential antibacterial activity on Bacillus cereus KCCM 11773, Bacillus subtilis KCCM 11316, Staphylococcus aureus KCCM 40050, Escherichia coli KCCM 11234, Klebsiella pneumoniae KCCM 11418, and Proteus vulgaris KCCM 40211.