Dutch Grandmaster (1976) born in Russia, Editor and author. Dutch Champion in 1973 and 1979. FIDE Senior Trainer (2004). In 1944 he moved to Leningrad where at the university he studied economic geography.
He played in the 1967 USSR Championship in which he tied for the twenty-seventh place. In 1972, he emigrated to Israel and two months later, he moved to the Netherlands and started his career as a professional chess player.
Sosonko took part in all the Olympiads held from 1974 to 1988 as a member of the Dutch team and later as the team captain. He won two individual medals: gold at Haifa 1976, bronze at Nice 1974, and two team medals: silver at Haifa 1976, and bronze at Thessaloniki 1988.
In 1975, he won the Zonal FIDE at Barcelona. Participated in the Interzonal Tournaments of Biel in 1976, where he finished in twelfth place and in 1985 in Tunis, finishing sixth-eighth. Among his participation in international events, he was equal first with Efim Geller at Wijk aan Zee in 1977 and with Jan Timman in 1981, won Lugano 1976 and Nijmegen in 1978. In 1984, he drew an exhibition match with Jan Timman with the score of 1-1. Finished fifth at Tilburg in 1979, in 1980 tied for the fourth place with Boris Spassky, and in 1982, he was equal third with Ulf Andersson. In 1983, still in Tilburg, he shared the fourth place with Rafael Vaganian.
In 1975, he won a match with max Euwe 1½-½.
Editor of New in Chess Yearbook since 1999 and the author of Russian Sillouhette(2005), The Reliable Past (2005), Smart Chip from St. Petersburg (2006), The World Champions I Knew (2013), The Rise and Fall of David Bronstein (2017), Evil-Doer: Half a Century with Viktor Korchnoi (2018).