Towards the end of 1946, he successfully passed with a First Grade in the University of Cambridge School Certificate and was admitted to the Wesley College of Education, in Kumasi.

There he read and obtained from the University of London his Bachelor of Arts (Hons) degree in History on July 31, 1953.

Prior to joining the Ghanaian Foreign Service in April 1959, Otoo taught History, Latin, English and Current Affairs at Mfantsipim School.

[3] In November 1963, he was moved to the Ministry of Defence to serve as its Principal Secretary (now Deputy Minister).

Between May 1966 and July 1970, he was appointed Second Secretary to Ghana’s Permanent Mission at the United Nations, New York, and head of the Economic, Information, and Cultural Department of the Ministry of Foreign Affairs.

[3] On 9 December 1982, he was called out of retirement and appointed Ghana's ambassador to the United States of America with accreditations to Mexico, the Virgin Islands, Belize, and Saint Kitts and Nevis.

[3] He presented his credentials on 17 March 1983 and served in this capacity at the highest diplomatic rank, until 18 October 1990.