Freshwater scarcity is a growing global concern, particularly in arid and semi-arid regions. Solar distillation presents a sustainable solution for water purification. This study aimed to optimize the performance of a hemispherical solar still (HSS) integrated with evacuated tube collectors (EVT) by analyzing the relationships between operational parameters and water productivity using response surface methodology (RSM). A modified hemispherical solar still (M-HSS) system was developed with integrated evacuated tubes. Experiments were conducted in Suez Governorate, Egypt, using varying numbers of evacuated tubes ranging from 2 to 16, water heights of 1, 2, and 3 cm, and operating times from 8:00 h to 18:00 h. A quadratic model was developed using Design-Expert software to predict water productivity, and statistical analyses were performed to evaluate model accuracy. The quadratic model demonstrated excellent predictive capability with R2 = 0.9874. Time emerged as the most influential parameter with an F-value of 3435.42, followed by the number of evacuated tubes with an Fvalue of 1196.58, while water height had a relatively minor impact. The optimal operating conditions were 18:00 h, 16 evacuated tubes, and a water height of 1.001 cm, yielding a maximum water productivity of 5162.668 mL. Experimental validation confirmed the model's reliability with only 0.06 % deviation between predicted and actual values. Furthermore, the modified system achieved a remarkable 551.11 % improvement in productivity, 54.95 % energy efficiency, and reduced production costs to 0.00325 USD/L compared to traditional systems. Integration of evacuated tubes with hemispherical solar stills significantly enhances water productivity, energy efficiency, and economic viability. The RSM approach effectively captured system behavior and identified optimal operating parameters, providing a valuable framework for designing more efficient solar desalination systems.