Persimmons (Diospyros Kaki. L) were dried using a 1.8 m2 flat plate solar collector connected with a drying chamber under three different drying temperatures of 45, 55, 65oC and slice thickness of 0.5, 1.0 1.5cm to examine the retention of vitamin C during drying. It took 13 hours when persimoons were dried at 65oC, 16 hours under 55oC and 18 hours under 45oC to reach to less than 10% moisture content with an average drying rates of 0.12, 0.14 and 0.15 gH2O.gd.m -1 respectively. Analysis of variance was done using two factorial completely randomized design. The analysis of variance showed that both the factors significantly (α<0.05) affected the retention of vitamin C in persimmons.The mean comparison showed an increase in drying temperature from 45 to 65oC caused an increase in moisture loss and drying rate while a decrease in vitamin C content of persimmon slices. Similarly increase in slice thickness from 0.5 to 1.5cm caused a decrease in moisture loss and drying rate per hour while increasing in retention of vitamin C in persimmons. The correlation between vitamin C content of persimmon at different slice thicknesses and drying temperatures showed that there is a strong negative correlation between drying time and moisture lost and drying rate with values of -0.991 and -0.997. It was concluded that persimmons may be dried at a temperature lower than 50oC and slice thickness more than 1.0 cm to get dried persimmons rich in vitamin C.