This research aims to investigate the single-slope solar still for treating industrial wastewater using stearic acid as a phase change material. The phase change material is macroencapsulated in aluminum bottles. The experiment is run at 50% wastewater depth with 9 kg (scenario 1), 12 kg (scenario 2), and 15 kg (scenario 3) mass of stearic acid and without stearic acid (scenario 4). The total output productivity of 2247, 1600, and 1359 mL m⁻²d⁻¹ is achieved in scenarios 1, 2, and 3, respectively, out of which evening time productivity is 24.47%, 22.18%, and 28.39% increasing the operational time by 5 h. The system is well efficient in reducing total dissolved solids and total kjeldahl nitrogen and chemical oxygen demand with an efficiency of 90.45%, 98.57%, and 97.89%, respectively. A notable increase of 78.92%, 36.63%, and 32.67% in thermal efficiency is attained using 9, 12, and 15 kg mass of stearic acid respectively compared to traditional solar still. Comparing scenarios based on thermal efficiency, it can be concluded that thermal efficiency and mass of phase change material are inversely related and lower masses show better performance efficiency.