Nanofluid is prepared through the nanoscale particles suspended in a fluid base and Nanotechnology is a new attempt to investigate the thermal sciences. As a result of huge investment in developed countries on nanotechnology, research on thermal properties of nano-fluids is of particular interest.Due to the usage of nanotechnology to reduce energy waste, in this project CeO2 with EG is used to prepare the nanofluid. For stabilization of nanofluid ultrasonic wave is used and viscosity is measured by digital viscometer. In this paper, the effects of temperature and volume fraction on viscosity of nanofluids are considered. This study indicated that the viscosity decrease in all concentrations when temperature is increasing and it increases with additioning volume fraction of nanoparticles. Also, the results show that viscosity changes related to temperature at higher concentrations. After deliberation of rheological properties and laboratory characteristics the exact formula for nanofluids viscosity obtained according to temperature and volume fraction to high accuracy. تفاصيل المقالة