It is now generally recognized that a high calorie diet with inadequate physical activity results in overweight or obesity, which in turn could lead to many disease. The most significant trend in soft drinks has been towards to use the high intensity low calorie sweeteners in recent years. Aspartame and acesulfame-k are the most successful approved high intensity sweeteners. Other properties of sugar such as mouthfeel are difficult to be achieved using high intensity sweeteners alone. Pectin can be classified as a low calorie bulking agent. It is of great interest because of its thickening properties. In this study, diet sour cherry syrup using aspartame and acesulfame-k as high intensity low calorie sweeteners and pectin as a bulking agent was formulated. In first part of this study, sensory evaluation of 36 formulas was measured and the best formulas were selected. Results showed that aspartame can easily be used to produce diet sour cherry syrup similar to the reference (containing sugar) sample but acesulfame-k showed that can not be used to make the syrup similar to the reference in any concentration. Sensory evaluation of the formulas having 0.4% aspartame and different percentage pectin (0.4%, 0.8% and 1.2%) had no significant differences with the reference. In second part of this study the effect of period of storage (1, 2 ,3 and 4 months), temperature (room temperature and 40 °C) and type of formulation (diet syrups containing 0.4%, 0.8% and 1.2% pectin) on sensory evaluations, viscosity and aspartame, anthocyanins and pectin stability were investigated. Results showed that time and temperature had significant (p 0.001) effects on sensory properties and aspartame and anthocyanins stability but had no significant effect on pectin stability. Since type of formulation (different percentage of pectin) had no effect on sensory evaluation and stability of aspartame and anthocyanins and more ever viscosity of diluted syrup which contains 0.4% aspartame and 0.4% pectin was similar to diluted reference syrup and regard to economic aspects of the production, formulation containing 0.4% aspartame and 0.4% pectin was selected as the best formulation. Shelf life of the product was determined about 2 months at room temperature and one month at 40 °C.