Ioannis Ketseas played tennis at the 1906 Olympics and was 1907 Pan-Hellenic Champion in both singles and doubles. He also competed in athletics, as a high jumper, and in rowing, winning a silver medal in coxed fours at the 1909 Pan-Hellenic Games. Ketseas was President of the Hellenic Athletics Federation from 1929-32, the Hellenic Tennis Federation from 1939-46, and Secretary-General of the Hellenic Olympic Committee from 1939-46. In business, Ketseas was a director of the National Bank of Greece and also served as the Greek Minister of Foreign Affairs.
In the 1930s Ketseas and Germany’s Carl Diem developed the concept of an International Olympic Academy (IOA). This would become a reality in 1961 and Ketseas was the first Chairman of the Council of the IOA until his death in 1965. Ketseas had become an IOC Member in September 1946, remaining on the Committee until his passing.