He has cited Justice Fazal Akbar as an inspiration to study law. Hossain moved to England from the U.S. in 1958, traveling to London by ship. In England, he met future professor Rehman Sobhan. In 1959, Hossain received a Bachelor of Civil Law degree from the University of Oxford and enrolled as a barrister in Lincoln's Inn. He also enrolled as an advocate in the High Court of East Pakistan. Hossain received a Doctor of Philosophy degree in international law from Oxford in 1964, with his dissertation "State Sovereignty and the United Nations Charter".