whose thermal conductivity is order of magnitude or two higher than the one of base fluid, increases thermal properties of the prepared nanofluid. Different researchers have obtained various results, from dramatic increase to values of thermal conductivity lower than the base fluid. Some of the proposed theories for the increase in properties include Brownian motion,aggregation of nanoparticles, nanolayer of ordered liquid molecules at nanoparticle-liquid interface and other. Some of the investigations of iron oxide nanofluids show that thermal conductivity increases with the increase of temperature, while the relative conductivity is almost constant. Results also show the enhancement of the thermal conductivity of the nanofluid as a function of volume fraction of iron oxide nanoparticles. The highest investigated volume fraction of nanoparticles