This paper describes an experimental investigation into the condensation of binary vapor flowing horizontally across the ideal tube bundle. For both cases of water-ethanol and water-methanol, data have been obtained at the near atmospheric pressure for vapor mole fraction in the range of 0-1 and at the vapor approach velocities in the range of 2-10 m/s for water-ethanol and 5-6 m/s for water-methanol. The results show that the heat transfer coefficient has a characteristic relationship with the mole fraction of the volatile species in the vapor. This relationship is considered to be caused by the gas phase mass transfer resistances. The results are also compared with the some theories for the binary vapor condensation.