The performance of a cylindrical parabolic concentrator with focal pipe - coupled with a developed solar still with (oil heat exchanger, Phase Change Material (PCM)) have been experimentally investigated to improve the freshwater productivity. The cylindrical parabolic concentrator with focal pipe and oil heat exchanger (serpentine loop) represent the external heat source to increase the temperatures of the basin water and PCM. The PCM used as a heat storage medium. The influences of high heat exchanger oil temperature on the performance of the developed solar still are experimental investigated. A comparison between a developed solar still and the convenstional solar still is carried out to evaluate the enhancement in the freshwater productivity under the same ambient conditions. The experimental results indicated that, the freshwater productivity approximately reached 10.77 L/m(2) day for the developed solar still, while its value is recorded 4.48 L/m(2) day for conventional solar still. The freshwater productivity of the developed solar still is 140.4% higher than that of the conventional solar still in average. Also, the daily efficiency approximately reached 25.73% for the developed solar still, while its value is recorded 46% for conventional solar still. The percentage decrease in the daily efficiency for the developed solar still about 44% compared to the convenstional solar still in average. In the present experimental work the estimated cost of one liter of freshwater productivity reaches approximately 0.1359 LE (0.0174 $) and 0.1378 LE (0.0177 $) for developed solar still and conventional solar still, respectively. This results is obtained during the period from June to August 2015 under the Egyptian conditions. (C) 2017 Elsevier Ltd. All rights reserved.