This paper analyse the role of scientific diplomacy in circulation of environmental knowledge across west-East divide in 1956 - 1966. This decade was crucial for Soviet scientists in reviving the old ones and establishing new international communications after isolation during the late Stalinist period (1948 - 1953). Moreover, in 1956 -57 the Soviet science was able to overcome interwar marginalization, and the Soviet Union was accepted to the main international scientific unions such as ICSU, which was crucially important for Soviet participation in the International Geophysical Year (IGY, 1957 – 58). Necessity to act fast and to combine ability to invoke and keep international connections simultaneously with fostering state patronage in highly changeable and often uncertain political milieu of Cold War encounters put at front the new leaders. They assembled diverse networks which included newly organized or reorganized institutions, well-trained staff many of whom had pre-War field work experience especially in the Arctic and rapidly developed material structures such as large research vessels, observational infrastructures, collections, data storage. Soviet efforts were coupled with a deep interest among many European and American environmental scientists especially inf the fields of polar studies and oceanography to the results of Soviet research. Some of them, like British geographer Terence Armstrong, served as mediators between eastern and western scientific communities. This paper is based on archival research and original database of international events in which Soviet environmental scientists participated, translations and reviews of Soviet publications during 1956-1966. I would like to acknowledge support from the Basic Research Program of the National Research University Higher School of Economics in 2012 for the project “Circulation of Knowledge in Divided World: Attraction, Confrontation, Cooperation among Communities of Experts in the Cold War Period”.