The objectives of this study were to develop complementary foods from the blends of cowpea with sorghum and maize. The complementary food formulations in the present study were based on locally available low-cost food materials commonly consumed in Ethiopia. Eight complementary food formulations were developed from maize + cowpea, germinated maize + cowpea, co-fermented maize+ cowpea, co-fermented and germinated maize + cowpea, sorghum+ cowpea, germinated sorghum+ cowpea, , co-fermented sorghum+ cowpea and co- fermented and germinated sorghum+ cowpea. The effect of natural co- fermentation with germinated sorghum and maize cultivars on TTA and pH, proximate value, anti-nuritional factors (tannin and phytate); minerals (Ca, Fe, and Zn), functional properties and sensory characteristics were investigated. Flours were co -fermented at room temperature (20- 230 C) for 72hrs at 1:3 dilutions (w/v). Samples were drown immediately at the end of each fermentation period and the samples were dried using a freeze drier. The overall results indicated that nutrient content of maize + cowpea was gave 14.37% crude protein, 4.48% crude fat, and 67.74 % carbohydrate. Germinated maize + cowpea exhibited 15.62% crude protein, 4.27% crude fat and 67.36% carbohydrate. Co-fermented maize+ cowpea show that 15.69% crude protein, 3.97% crude fat and 69.93 % carbohydrate. Co-fermented and germinated maize + cowpea exhibited 16.00% crude protein, 3.43% crude fat and 70.84% carbohydrate. Sorghum+ cowpea gave 15.90%, crude protein, 3.48 % crude fat and 66.47% carbohydrate. Germinated sorghum+ cowpea had show 16.53% crude protein, 3.33% crude fat and 66.25% carbohydrate. Co- fermented sorghum+ cowpea was show that 16.66% crude protein, 3.24% crude fat and 69.22 % carbohydrate and the last co- fermented and germinated sorghum+ cowpea exhibited 16.95% crude protein, 3.11% crude fat and 70.02% carbohydrate. Co-fermentation caused an increase in protein, TTA, energy content, carbohydrate and improved mineral bioavailability and decreased fat, ash, crude fiber, viscosity, antinutritional factors. Germination increased significantly (P