Background and Objectives: Breakfast cereals substantially contribute to daily energy and nutrient intakes among children. Also consumer interest in naturally colored foods such as breakfast cereals is growing. The purpose of this study was to investigate the use of pumpkin powder in breakfast cereal production and to determine the physicochemical and sensory properties of the product. Materials & Methods: In this study, the Effects of corn flour replacement with pumpkin powder at six levels of 0, 5, 10, 15, 20 and 25 percent were investigated on the sensory properties and physicochemical properties of breakfast cereals. The characteristics of prepared product including fat, fiber, moisture, protein, ash, β-carotene, polyphenols and color were evaluated. Results: The results of this study showed that adding pumpkin powder did not have a significant effect on fat and protein content (P>0.05). The results of tests for moisture, ash, polyphenols, β-carotene and color showed significant differences (P>0.05) compared to the control sample. With increasing substitution of pumpkin powder, fiber and β-carotene content of breakfast cereals significantly increased. Results of image processing showed that by adding pumpkin powder, the color of samples were redder and more yellow. According to the results of sensory evaluation, the breakfast cereals containing 15 percent pumpkin powder was identified as a good sample. Conclusion: According to the physicochemical and sensory test results, samples containing 15% of pumpkin powder was the best treatment.