Flat plate solar collector (FPSC) is commonly used due to its low price, less complexity, and easier installation and operation. The low thermal efficiency is the main disadvantage of this type of solar collectors. In the present study, the thermal performance of the FPSC using alumina oxide -water and copper oxide -water nanofluids are evaluated. The effect of nanoparticle volume fraction and nanoparticle type are investigated theoretically and validated experimentally. A computational fluid dynamic model is developed. The model is validated with experimental result carried in this study. The model is simulated under the hot climate conditions of Egypt. The results showed that the presence of the nanoparticles in the working fluid of the FPSC increases the pressure drop in the collector, but thermal performance enhancement is also obtained. Further, an optimum nanoparticles volume fraction of 0.5% of copper oxide nanoparticle is found to attain the highest thermal efficiency of the collector. Furthermore, using copper oxide-water nanofluid is effective than using alumina oxide-water nanofluid at the same conditions.