Abstract: CFD investigations have been carried out in this paper to study the temperature difference for cross flow heat exchanger with smooth tube and low integral finned tube. The study includes geometry creation with dimensions (2505001200) mm width, height and length, respectively. has a single copper tube with eight passes.. The low integral finned tube with (19 mm) inner diameter, (21 mm) root diameter and (24 mm) outer diameter . The fin height is (1.5 mm). Air is assumed as a cooling fluid passing across the test tube with a range of velocities (1, 2, 3 and 4) m/sec. The inner side flow rates with a range of (2, 3, 4, 5 and 6) L/min. for water. The water temperatures at the inlet of test tube were (50, 60, 70, 80) °C. The results showe that the temperature difference and heat transfer coefficient for heat exchanger with finned tube is higher than with smooth tube.