Evaluate of combined treatments between hot water and potassium sorbate for controlling sour rot disease of lemon fruits was studied. Results under in vitro trails revealed that the lethal temperatures to G. citri-aurantii were 56.0 and 58.0 oC when were exposed to temperatures for 30 and 10 seconds respectively. Meanwhile, complete reduction in linear growth of G. citri-aurantii was achieved with potassium sorbate at 15.0 g / L. The highest reduction was obtained with PS at 12.5 g / L which reduced the linear growth by 75.4%. Moreover, under in vivo trails results indicated that all tested hot water temperatures for all tested exposure times significantly reduced the sour rot incidence and severity of Lemon fruits. The most effective treatment was hot water at 60 oC for 30 seconds which reduced sour rot incidence and severity by 81.0 and 84.0 % respectively. On the other hand the highest reduction in sour rot incidence or severity was obtained with potassium sorbate at 12.5 and 15.0 g / L which reduced the disease incidence by 82.0 &82.5 and severity by 85.0 & 86.0 % respectively . Furthermore, combined treatments between hot water at temperatures of 60oC for 30 seconds and potassium sorbate at 12.5 or 15.0 g /L. reduced the disease incidence by 91.0 & 92.0 and severity by 93.0 & 94.0 % respectively . Meanwhile, single treatment of hot water at temperatures of 60oC for 30 seconds and potassium sorbate at 12.5 or 15.0 g /L. reduced the disease incidence and severity more than 76.0 and 78.0 % respectively. It could be suggested that hot water combined with potassium sorbate are excellent treatments for controlling sour rot disease of Lemon fruits .