The paper presents the results of experimental investigation of heat transfer and hydrodynamics during condensation of moving steam in a narrow channel of square cross-section 2 mm x 2 mm. The channel had a serpentine shape, the channel length was 660 mm. An experimental cell simulated conditions of heat transfer in the condenser of loop heat pipes. The steam velocity at the channel inlet ranged from 13 to 52 m/s, the pressure was 1 atm. The temperature of the cooling water varied from 70 to 95 degrees C. The annular flow pattern was noted in the whole range of the regime parameters. There was a clear boundary between the condensation zone and the zone occupied by the condensed phase downstream. Temperature has measured along the channel, and the heat-transfer coefficients have been determined. The coefficient values varied from 10,000 to 55,000 W/K m(2) depending on the steam velocity at the channel inlet and the cooling temperature. The efficiency of the condenser - heat exchanger has been investigated. (C) 2009 Elsevier Ltd. All rights reserved.