In this study, an attempt was made to compare the thermal performance of two identical single-slope solar stills using a different number of covers (single cover and double cover). These experiments were carried out at the Tractors and Agricultural Machinery Research and Testing Station - Agricultural Engineering Research Institute - Alexandria at 31.2 °N latitude, 29.92 °E longitude and 15 meters above sea level. The experiments were conducted from the 1th of May to the end of June 2022.  Various climatic factors and measurements of solar stills were monitored, measured and recorded. The average solar energy available per hour within solar wind speed and ambient air temperature during daytime,  432.82 W, 3.89 m/s, and 26.18 C° . The thermal efficiency for the single-slope solar still of double cover was higher than that of the other single-slope solar still (single cover) about 5.6%. The distillation efficiency for the single-slope solar still of single cover was higher than that of the other single-slope solar still (double cover) by 8.8 %.