An experimental study of flow boiling of binary organic solution was conducted in a horizontal tube. An organic mixture of miscible fluids, chlorodifluoromethane (R22)-dimethylacetamide (DMAC) was circulated through the experimental system. The influence of the heat source, flow rate, solution concentration and operating pressure on the flow characteristics and the heat transfer coefficient was examined experimentally. Based on the experimental observation an appropriate flow pattern map was constructed. The experimental values of the heat transfer coefficient (HTC) were compared with predicted HTC obtained by several known correlations. Based on these comparisons the well know Dittus & Boelter correlation deviated up to 30%. A better agreement (up to 15%) was obtained by modified the Kattan et al. [10-12] correlation. The modification includes using the Forster and Zuber correlation [21] for nucleate boiling HTC and multiplying the predicted HTC by a constant of 1.4. (C) 2009 Elsevier Ltd. All rights reserved.