Nanoparticle plays a vital role in heat transfer application considering this advantage, we synthesized zinc oxide nanoparticle using modified sol-gel method and characterized it using X-Ray Diffraction (XRD), Field Emission Microscopy (SEM) and High-Resolution Transmission Electron Microscopy (HRTEM). XRD and HRTEM confirm that synthesized nanoparticle is pure zinc oxide nanoparticles, with an average size of about 20 nm. Further, it is dispersed with the water to get ZnO-water nanofluid. Four samples of ZnO nanoparticles having a volume fraction of 0.01%, 0.1%, 1% and 5% are dispersed in water and sonicated for 2 hours. After sonication, thermal conductivity analysis of ZnO-water nanofluid is done by KD2 Pro. The thermal conductivity of nanofluid is compared with the base fluid. 0.01% doping shows no significant enhancement of thermal conductivity but 0.1%, 1% and 5% shows 0.5%, 4.5% and 23.7% thermal conductivity enhancement respectively. Therefore, ZnO-water nanofluid is a good thermic fluid for future heat transfer applications.