The material development project on supercritical water-cooled reactor (SCWR) launched in 2004 as an international nuclear research initiative (I-NERI) project in Japan. This project consists of three sub-theme; 1. material/design compatibility, 2. irradiation properties, 3. complex effects of irradiation and SCW corrosion. In the first sub-theme, the test items, test conditions and criteria are determined through the survey on the requirement for the reactor core materials in terms of mechanical properties, phase stability, corrosion behavior, and SCC properties. In the second sub-theme, JMTR (Japan Materials Testing Reactor) and Experimental Fast Reactor JOYO were selected as irradiation test reactors considering their neutron flux, capable fluence and irradiation temperature. Post irradiation examination (PIE) is conducted for microstructure, mechanical strength, hardness and creep deformation. In the third sub-theme, general corrosion tests are conducted in supercritical water after the neutron irradiation. Besides the neutron irradiation tests, material evaluation tests are being carried out using un-irradiated specimens to understand basic properties of test materials in the temperature range of SCWR. This paper describes the framework and the interim results until the third year of the 4-year program.