An ink-jet printing head assembly having a substrate and a cover plate which are juxtaposed with a space provided therebetween, for a nozzle at one edge of said substrate, an air chamber behind said nozzle, and an ink chamber with an outlet into the air chamber beyond the air chamber. A first electrode is located along an edge of the inner surface of the substrate and on one side of the nozzle. A second electrode is located on the inner surface of said substrate in the outlet opening between the ink chamber and the air chamber and separated from the first electrode by a space. The printing head ink used is conductive. The surface tension of the ink prevents it from flowing out of the small outlet from the ink chamber into to the air chamber when air is flowing into said air chamber and out of the nozzle. When a voltage is applied across two electrodes the electric field between the electrodes creates an attractive force the overcomes the surface tension of the ink in the outlet and ink flows into the air chamber where droplets are formed and the air transports the to an object to be printed. A printing head assembly according to the invention having electrodes and nozzles with a high concentration per unit area can be realized by means of a film formation technique. Such a compact and lightweight designed printing head assembly with a high concentration of nozzles can be manufactured using mass production techniques.