This paper examines the historical development of technological capabilities in Korean steel industry focusing on the case of POSCO (Pohang Iron & Steel Co.). Technological capabilities of POSCO have been developed through acquisition, catch-up, and generation stage. In the 1970s standardized operation technologies were acquired based on Japan's technological cooperation. The prime route of technological acquisition was overseas training and operation technologies were more articulated by real operation. In the 1980s POSCO focused to catch-up ad-vanced technologies through in-house R&D activities. Technological information was broadly accumulated, task force teams were constructed for important technological tasks, and the scope of technological innovation covered nearly all fields. Since the 1990s POSCO launched long-term projects based on the large-scale investment and challenged the new fronts of steel technologies. Frontier technologies such as smelting reduction and thin slab casting were early commercialized and new technological concepts were emerged. In conclusion, this paper suggests some implications on the development of technological capabilities in Korea.