Abstarct: Abstract This research investigates a hemispherical solar still system, with the primary goal of studying and improving the efficiency of freshwater production from saline water. The geometric schematic of the system includes a transparent spherical cover, an absorber basin, and a reflector. Solar radiation, after passing through the hemispherical cover, is absorbed by the absorber basin and transferred to the water, which causes the water to heat up and initiate the evaporation process. The resulting water vapor condenses upon releasing its latent heat on the inner surface of the hemispherical cover, and the condensed water is guided downwards and collected. The temperature of the hemispherical cover and the effect of wind on it are key factors in this process. In this study, the effect of using a reflector on the temperature changes of the system components (water, glass cover, and basin) during the day was investigated. Solar radiation and wind speed data were collected and used for the southern regions of the country (with access to saline water). The results showed that solar radiation follows a specific pattern during the day, increasing in the early hours of the day, reaching its peak around noon, and then decreasing in the afternoon. Also, solar radiation varies in different months of the year, reaching its maximum in July and August. Wind speed is variable throughout the day, and in September, the wind speed is relatively higher than in other months. Studies showed that the temperature for water and the basin follow a similar pattern and change under the influence of solar radiation during the day. The rate of temperature change in the basin is faster than that of saline water, which is due to the higher thermal inertia of saline water. Also, due to its higher heat capacity, saline water absorbs and releases the heat absorbed from solar radiation at a slower rate. The results of the average accumulated distillation over three months showed that the use of a reflector has a significant effect on increasing the amount of distilled water, so that the amount of distillation in the presence of a reflector increased by an average of about 100 liters compared to the case without a reflector. The highest distillation rate was also observed in August. Also, by adding a reflector, the system efficiency increased by about 10%. These findings demonstrate the high potential of using reflectors to improve the performance of hemispherical solar still systems.