This thesis explores the progress in, and the obstacles obstructing, the building of comprehensive security between Russia and South Korea since diplomatic relations were established in 1991. It focuses on oil and natural gas projects, linking the Trans-Siberian and Trans-Korean Railroads, industrial development in the Nakhodka Free Economic Zone, fishery cooperation, and the arms trade, and examines whether these five aspects of cooperation serve to contribute to building Russian-South Korean bilateral and regional economic security. The study pays particular attention to three aspects of security: definitions of economic, comprehensive and regional economic security, the security building process between states, and security threats. The thesis argues that in order to establish a favourable bilateral and regional economic security environment, bilateral and multilateral cooperation is essential because it generates trust and confidence between nation states. Although Russia and South Korea have emphasized both traditional and non- traditional security cooperation, the focus of the security building process has gradually changed from traditional military and strategic concerns to non-traditional economic dimensions. The two countries have been engaged in enhancing bilateral and regional economic security in the regions of the Russian Far East and the Korean peninsula since 1991. The thesis argues that energy, transport networks, the Free Economic Zone project, fishery cooperation, and the arms trade all have the potential to enhance comprehensive bilateral security and further regional economic security in Northeast Asia. However, Russian-South Korean economic cooperation has been hampered by a number of obstacles, including domestic factors on both sides, and external factors such as the unresolved North Korean nuclear issue. In each of the five projects studied, the obstacles have been greater than the progress that has been made. In sum, the obstacles have prevented Russia and South Korea from fulfilling their potential for creating a cooperative comprehensive security relationship.