The present work demonstrates the encapsulation of silver nanoparticles into micellar structures of the diblock copolymer (DBC) consisting chemically complementary methoxypoly (ethylene oxide) and poly(acrylic acid). The reduction of silver ions to silver nanoparticles or nanoclusters is achieved by an excess of sodium borohydride in the DBC aqueous solutions with various pH. The formation of considerably more smallest and stable Ag-nanoparticles in the DBC micellar solution at pH = 3 compare with the test of an Ag(+)solution without DBC micelles was revealed. The morphology of Ag-nanoparticles dispersed within DBC matrices and their average particle size were indicated by TEM images.