A heat-transfer material includes a tubular body made of a metal. The body includes on an inner surface thereof a porous electroplated layer having re-entrant cavities. A heat transfer material is produced by: preparing a body of a metal serving as a cathode and forming a hydrophobic film on a surface of the body; subsequently keeping the surface of the body and an anode in contact with a plating aqueous solution; and subsequently applying a direct electrical potential betwee the anode and the cathode to cause plating current to flow through the plating solution to lay deposits of plating metal on the surface of the body and laying a number of particulate bubbles on the hydrophobic film on the surface of the body so that the bubbles are enveloped by the metal deposits to form on the surface of the body a porous plated layer having re-entrant cavities.