Abstract: Disclosed is a method of heat transfer between a solid such as a metal and a fluid such as water or air characterized in that a porous layer having numerous pores of a nano-size is formed on a surface of the solid that is in contact with the fluid, by treating the surface of the solid with a paste containing a particle group such as copper oxide (CuO), carbon (C) or alumina (Al2O3) having a diameter of 100 nm or less and an acid or an alkali. A completely novel method exhibiting an extremely high efficiency with a low cost is provided regarding the convective heat transfer among the heat transfer phenomena.