An experimental study on the direct contact condensation (DCC) of steam jet in subcooled water flow in a rectangular mix chamber was conducted. A high-speed camera was employed to record the flow field of DCC in the visualized experimental rig, in which, the steam nozzle and water nozzle were both rectangular. The flow field was filmed when the steam mass flux, water mass flux and water temperature were in the range of 200-600 kg/m(2) s, 6000-18000 kg/m(2) s and 293-333 K, respectively. The results indicated that, the flow field of DCC in the rectangular mix chamber consisted of four regions, and they were steam region, interface, mixture layer and ambient water region. The interface between steam region and mixture layer was clearly observed. The flow pattern of DCC was performed as bubble flow, oscillatory jet, stable jet and divergent jet at various test conditions. The steam region dimensionless penetration length and average heat transfer coefficient of the stable jet were found to be in the range of 1.73-4.40 and 2.89-7.89 MW/m(2) K, respectively. Furthermore, an analytical model was established and a correctional correlation was developed to predict the dimensionless penetration length. An empirical correlation was proposed to predict the average heat transfer coefficient. (C) 2014 Elsevier Ltd. All rights reserved.