The primary purpose of writing this book is to make available to the students, researchers and is prepared for case study projects. This research involving evaluation of the thermo-physical properties of Ethylene-glycol based solar thermic fluids oxidized multiwalled carbon nanotubes. Nano fluids were prepared with Ethylene glycol and water as base fluids in 100:0, 90:10 and 80:20 ratios. These base fluids of three categories were dispersed with purified and oxidized multiwalled carbon nano tubes (MWCNTs) in the weight fractions of 0.125, 0.25 and 0.5 percentages. The variation in zeta potential is studied to examine the dispersion stability during a period of 2 months. Thermal conductivity and dynamic viscosity were measured by hot disk method and Anton paar viscometer respectively. Significant enhancement of thermal conductivity by 15 to 24 % was observed when the bse fluids are dispersed with MWCNTs. Dynamic Viscosity of nanofluids is found to be higher compared to base fluids in the temperature range of 50 to 70 ºC. A comprehensive mathematical equation suitable for all weight fraction of MWCNTs and volume percentages of Ethylene glycol was developed.