A novel technique for formation of metal lines for electronic devices, and for reduction of resistivity in such metal lines, is proposed. In the technique, the metal lines are formed in trenches by using functional liquids containing metal nanoparticles. The trenches are constructed on a plastic substrate by imprint of a patterned mold. When the whole surface of the plastic substrate is covered with a hydrophobic film, the hydrophobic property disappears only in the trenches due to the pressing process of the imprint, and thus the functional liquid automatically accumulates into the trenches. When the metallic functional liquid is modified with tween-20 (polyoxyethylene-20), metal lines with a width of 10 mu m are formed by capillary effect. The resistivity of such metal lines can be lowered to the order of 10(-6) Omega cm by exposing them to hydrogen atoms generated in vacuum by catalytic cracking of hydrogen molecules with heated tungsten wires. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3456179]