With urging needs to decrease the fuel consumption and environment pollution, energy saving and emission reduction technologies in the ICE (internal combustion engine) industry are developed. A thermal OS/ORC (Oil Storage/Organic Rankine Cycle) system was constructed and preliminarily tested for WHR (Waste Heat Recovery) from exhaust gas of a 240 kW diesel engine. The heat balance test of diesel engine without OS/ORC was conducted first to investigate the varying property of exhaust gas, then the OS/ORC system was tested to show its ability against high temperature and variation of exhaust gas. The results show that thermal oil effectively dropped the working temperature of organic fluid to less than 210 degrees C, which is much lower than the decomposition temperature of many organic fluids. Also, thermal oil brought a significant inertia to the response of system which could be positive against the variation of engine condition. In order to learn more about the operating characteristics of OS/ORC system, the impact of important parameters on each other was investigated quantitatively as well as on the performance of OS/ORC system. The results show that within the given range, higher evaporating pressure can obviously improve the performance of OS/ORC while the impact of superheat is nearly negligible. (C) 2016 Elsevier Ltd. All rights reserved.