Mango is one of the leading fruits produced by smallholder farmers in Northwestern Ethiopia, especially in the midland and lowland areas of the Upper Blue Nile Basin. During the peak season, farmers are forced to sell their hard-earned produce at low prices, and a large part of the fruit was discarded due to deterioration as a result of high production volume and small local market demand. Production of packed fruit slices using drying is one of the methods that have been proposed to minimize postharvest loss of highly perishable fruit products. The objective of this thesis was to design and develop an affordable solar dryer for the production of mango slices. In this work, the cabinet-type solar dryer integrated with a rectangular shape baffles collector was designed, constructed, and its performance was evaluated. The effects of baffle and slice thickness on the drying characteristics of mango slices were investigated. The ascorbic acid, phenol contents, and rehydration ratio of the dry mango slices were in the range of 21.75–25.55mg/100 g, 97-180mg/100g, and 2.9-4.27 respectively. It was observed that ascorbic acid; phenol content, color, rehydration ratio, and sensorial attributes were affected by slice thickness and baffle. CFD Model of the dryer was developed and used to perform thermal analysis of the dryer. The temperature and RH results obtained from the model were validated by experimental data with an over-prediction of RH (7.8%) and underestimation of Temperature (4.35%) and the developed model was used to study the effect of air velocities, baffle number, and baffle cuts to rigorously analyze their effects on the solar collector outlet temperature and pressure drop. The optimal performance was determined based on the solar collector outlet's maximum temperature and minimum pressure drop. Based on the combined results from the experiments and optimized CFD model of the collector, 4 number of baffles with baffle cut of 25% and 1m/s inlet air velocity cabinet dryer was selected to be a viable alternative method for the drying of a 3 mm thick mango slices in terms of ascorbic acid (26.66±1.65 mg/100g), rehydration ratio (4.49±0.91) total phenolic content (84±1.34 mg/100g), sensorial test and color preservation on a large scale. The result of this study will have a significant contribution to reducing the postharvest loss of mango and improving the food security and livelihood of small scale farmers. Keywords: Baffle, CFD analysis, Design, Mango slice, Northwestern Ethiopia, smallholder farmers, color, Vitamin C, Rehydration