The novel, original method of antibacterial finishing of flat textiles by ink-jet printing with application of nano-silver has been developed. The silver particles were prepared by direct reduction of silver salt-containing ink on and into the fibres (in-situ method). The one- or two-nozzles' system was used on an industial ink-jet printer equipped with the Xaar 128-360 printing head. Silver finished fabrics were subjected to the surface examination using the scanning electron microscopy (SEM) with energy disperse X-ray spectroscopy (EDX) booster. The chemical state of nanosilver deposited on textiles was determined using X-ray photoelectron spectroscopy (XPS). Also, the size and size distribution profile of silver particles extracted to water were estimated by the dynamic light scattering method (DLS). The changes in silver content on fabric finished after multiple washings were evaluated by an inductively coupled plasma spectroscopy (ICP-ToF-MS) as well as by the laser ablation mass spectroscopy (LA-ICP-ToF-MS). Antibacterial efficacy of silver finished textiles against Bacillus subtilis and Escherichia coli was examinated by a qualitative method (Agar Diffusion Test). The results obtained proved an excellent durablity of silver-finished textiles even after 50 alkaline washings. The method is protected by 2 patent applications.