The application heat tranfer process has widely used in several areas of industry, one of regular device that used is heat exchanger that could be found in cooling system, refineries, power plant, etc. The commonly fluids used in heat exchanger were water, minral oil, and ethylene glycol which has poor heat transfer characteristic. Therefore, nanofluid was used to improve the heat transfer characteristic of fluid used in heat exchanger. This study added NiO nanoparticle (siintering and unsintering) into distlled water. This study aimed to determine the heat transfer characteristics of NiO nanofluid both sintering and unsintering by using laboratory-scale heat exchanger type of shell and tube. The experiment conducted in this study used the variation of flow rate (0.45,0.9, and 1.35 l/m). The test results indicated that the best performance of nanofluid was found at NiO-sinterting nanofluid. © 2020 American Institute of Physics Inc.. All rights reserved.