Abstract: The invention relates to colloidal solutions of silver nanoparticles and to method of it preparation and can be used in different areas, particularly in medicine, veterinary science, food industry, cosmetology, household chemistry and agrochemistry. Method includes the electrochemical dissolution of silver in the deionized water. The silver in fine powder form with chemical purity of 99.999% and with nanoparticle sizes up to 100 nm is subjected to electrochemical dissolution in electrolyser, within which are located the electrodes in form of containers made from chemically neutral material, in which fine powder of silver from 100 to 150 g are placed, and by means of conductor covered by chemically neutral coat the direct voltage ranges from 30 to 45 volts is energized. Electrolysis is proceeded under conditions of cycling voltage polarity every 2 hours and mechanical stirring of solution 2 times in twenty-four hours until the concentration of silver in colloidal solution from 5.0 to 100 mg/l.