Born Oct. 8, 1908, in Kellaki, Cyprus. Cypriot labor leader.
The son of a Greek peasant, Papaioannou took his first job in the mines on Cyprus, where he joined the labor movement. In 1930 he moved to Great Britain in search of work, and in 1931 he joined the Communist Party of Great Britain. In 1936 he fought in the National Revolutionary War in Spain (1936–39) as a member of the International Brigades. At the behest of the Central Committee (CC) of the Progressive Party of the Working People of Cyprus (AKEL), he returned to Cyprus in 1946 to become editor in chief of the party’s central organ, the newspaper Demokrates.
Papaioannou became a member of the CC of the AKEL in 1947. From 1947 to 1949 he was CC secretary for organizational affairs. In August 1949, at the Sixth Congress of the AKEL, he was elected a member of the Politburo and general secretary of the party. In December 1955 he was arrested. He fled from confinement in April 1956 and worked in the underground until December 1959. In 1960, Papaioannou became a deputy of the House of Representatives of the Republic of Cyprus.