Nanofluid is a new fluid with special characteristics that can be used in various industrial heat transfer applications. The nanofluid was created using the two-step approach of dispersing nanoparticles into Jatropha oil. The experiments were conducted for four samples of mixture nanofluid at four different volume concentrations of 0.5%, 1.0%, 1.5%, and 2%. The nanoparticles were characterized by X-ray diffractometric analysis, X-ray fluorescence spectroscopy, and scanning electron microscopy. The greatest increase in thermal conductivity for CuO–Jatropha oil nanofluids was made possible by 0.5%, 1.0%, 1.5%, and 2% mixture was 4.5%, 6.01%, 7.6, and 9.1%. The study observed that a mixture achieved the highest thermal conductivity for nanofluid at 2%. At a mixture of 0.5%, the lowest value of thermal conductivity within the range under consideration, a “deeding” effect was seen. To determine the thermal conductivity of CuO–Jatropha oil nanofluids based on temperature, volume concentration, and nanoparticle mixture volume concentrations, the study suggested and compared four sample models. The effect of nanoparticles on the rise of thermal conductivity and viscosity was investigated at temperatures ranging from 298 to 323 K. The X-ray diffractometer is used to characterize nanoparticles. Viscosity and thermal conductivity have been tested in the lab. The findings show that the copper oxide nanoparticles improved the base fluid’s thermophysical abilities more than Jatropha oil alone. For the evaluation of the thermal conductivity and viscosity of nanofluid, new empirical correlations were presented based on experimental data. The thermal conductivity of the nanofluids increases as the temperature rises, while the viscosity of the nanofluids decreases.