... a strong man of Medicine, distinguished in Physiology, [who] had written many scientific papers and had published two world renown Physiology books through Oxford University Press, for University level medical students. He loved his subject and thoroughly enjoyed talking about it. He was also a highly successful University teacher.James wrote about growing up with Gabriel :-
Gab as we all call him was my youngest brother and the favourite of all the brothers. We had an especially soft spot for each other and I particularly remember a day in the late 1930s coming back from the market with Mama who had all sorts of goodies for all the children, and as we got to the compound, a very young Gab spotted us and rushed out of the house towards us happily dancing and singing "James is back, James is back" as opposed to the more usual "Mama is back" and rushed and hugged me very warmly ... it was a special moment that captured and typified the strong bond and affection we had all our lives.The family moved to various places in Eastern Nigeria as James grew up and for a while they lived in Umunjam, Imo State. After attending several different schools as the family moved around, he entered the Dennis Memorial Grammar School, Onitsha, in 1944. This school was run by the Church Mission Society, founded in 1799 in the City of London, England, by men including William Wilberforce who, like all the founders, was passionately committed to the abolition of the slave trade. Another founder of the Church Mission Society was John Venn, the grandfather of the mathematician John Venn. The Dennis Memorial Grammar School was founded in 1925, nearly 70 years after the Society began its mission in the area. This long delay was due to the Society believing for a long time that its role was the propagation of Christianity for which secondary education was not necessary. During the period that Ezeilo attended the Memorial Grammar School its principal was E D C Clark who raised the standards of the school in arts, science and technical subjects.
Ezeilo graduated from the Dennis Memorial Grammar School in 1948 and, having achieved the highest marks in the University Entrance Examination, he entered the new University College Ibadan (now the University of Ibadan) in 1949 to study mathematics. The University of Ibadan was established in 1948 as a College of the University of London, England; it was the first university to be established in Nigeria. It became an independent university in 1962 after the country gained its independence from Britain. Ezeilo had a highly successful undergraduate career winning many departmental prizes, faculty prizes, and the University of Ibadan Major Scholar Award. In 1953 he graduated with a B.Sc. (First Class Honours in Mathematics) and in the following year he was awarded a B.Sc. Advanced Degree (with distinction). He then began postgraduate studies and received an M.Sc. in 1955.
The award of a Leverhulme scholarship enabled him to travel to England and matriculate at Queens' College, University of Cambridge, in 1955. He sailed from Lagos on the ship Aureol and arrived at Liverpool on 26 September 1955. From Liverpool he travelled to Cambridge. There was a number of world class mathematicians teaching at Cambridge during the years that Ezeilo studied there, including J W S Cassels, Michael Atiyah, Frank Smithies, Abram Besicovitch and Mary Cartwright. It was Cartwright who became Ezeilo's thesis supervisor and advised him during his research on ordinary differential equations. He was awarded a doctorate in 1959 for his thesis Some Topics in the Theory of Ordinary Non-linear differential Equations of the Third Order although he had submitted his thesis and had been examined in 1958. On 28 August 1958 he sailed from Liverpool on the Tamele, arriving in Lagos, Nigeria.
He began publishing papers based on the research he had undertaken for his Ph.D. The first few papers are On the boundedness of solutions of a certain differential equation of the third order (1959), On the stability of solutions of certain differential equations of the third order (1960), On the existence of periodic solutions of a certain third-order differential equation (1960), and A note on a boundedness theorem for some third order differential equations (1961). The results of the 1959 paper are of the same type as the ones obtained for second order equations by Mary Cartwright in her 1950 paper Contributions to the theory of nonlinear oscillations. In this 1959 paper, Ezeilo writes, "I should like to express my gratitude to Dr M L Cartwright for her help and guidance in the preparation of this paper. His address on the paper is Queen's College, Cambridge. On the first of the 1960 papers, Ezeilo gives his address as Ibadan and he gives the acknowledgement, "I am grateful to Dr M L Cartwright for suggestions leading to the widening of the scope of this paper." The 1961 paper, with address University College, Ibadan, Nigeria, contains improvements of the results of the 1959 paper.
After Ezeilo returned to Nigeria, he was appointed as Lecturer II in Mathematics at University College Ibadan in 1959. He returned to England in the summer of 1960, sailing from Lagos on the Accra to Liverpool, arriving on 11 July. He returned home a month later on the Apapa, sailing from Liverpool on 18 August on a voyage to Lagos. In 1962, the year the University of Ibadan became an independent university, he was promoted to Senior Lecturer in Mathematics and, in the following year, he went to the United States for a sabbatical year. He spent the academic year 1963-64 as a Visiting Lecturer and Research Associate at the Department of Mathematics, University of Michigan, Ann Arbor. On his return to the University of Ibadan he was promoted to professor in 1964.
Nigeria had become an independent country in 1960, ending its time as a British colony but the Biafran War broke out in July 1967. A military coup in 1966 was a significant factor in the outbreak of war which was fought between government forces and the state of Biafra which was seeking independence motivated by ethnic and religious differences. These events seemed to be the reason that Ezeilo left the University of Ibadan in 1966 to take up the position of Professor of Mathematics at the University of Nigeria, Nsukka. This university had been founded in 1955 although it only opened formally on 7 October 1960. Ezeilo became head of the Department of Mathematics in 1967 but, in July 1967, Nsukka became one of the first Biafran town to be captured by Nigerian forces. As a result of this, the University of Nigeria, Nsukka, was burned down and chaos resulted. The students at the University of Nigeria, Nsukka, had joined the Biafran army when was had been declared although they had no weapons. Few survived the attack by the Nigerian army.
The university had renamed itself the University of Biafra in July 1967 and it continued to have this name until January 1970 when the civil war came to an end. Ezeilo took up his position as head of the Department of Mathematics in 1970 but in November of that year he was appointed as Acting Vice-Chancellor. He held this position for four months until the appointment of Herbert C Kodilinye, a Professor of Medicine, as Vice-Chancellor. At this point Ezeilo returned to his position of head of the Department of Mathematics. The appointment of Herbert Kodilinye was not a great success, partly because the inhabitants of Nsukka became depressed after the Biafran war. He tried to remodel the university to give it the British Oxbridge collegiate structure. This, however, was not popular and there were rivalries between the academics which made it a difficult place in which to work. In 1975 Ezeilo was appointed as the Vice Chancellor, taking over from Herbert Kodilinye, and so became the fifth Vice Chancellor. He held this position until 1978 when he moved to Bayero University, Kano, as Vice Chancellor. This university only became independent in 1977 under the Vice Chancellor Mahmud Tukur, and Ezeilo became the second Vice Chancellor in 1978. This move had not been Ezeilo's choice, but rather :-
... the then military government posted him to the University from University of Nigeria, Nsukka, as part of its policy of posting Vice Chancellors to different universities.He only held this position in Kano for one year, however, for in 1979 he went to the United States for sabbatical leave being appointed Benedict Distinguished Professor of Mathematics at Carleton College, Northfield, Minnesota and then Visiting Professor of Mathematics at Howard University, Washington DC. The obituary  gives information about what Ezeilo achieved during his year as Vice Chancellor at Bayero University:-
Bayero University highly regards the late Anambra-born Professor as an erudite scholar of high standing, who has left indelible footprints on the sand of time, and who earned himself a page in book of academic exploits. Expressing the University's sympathy, the Vice Chancellor, Professor, Abubakar Adamu Rasheed, Member of the National Institute, Member of the Order of the Federal Republic, ... noted that the late University don had during his tenure as the Vice Chancellor exhibited rare traits of diligence, ingenuity and phenomenal scholarship. He said the former Vice Chancellor sacrificed his time by teaching some courses during his tenure at the University.After a year in the United States, Ezeilo returned to Nigeria in 1980, again taking up his position as head of the Department of Mathematics at the University of Nigeria, Nsukka. He held this post until :-
... 1988, when he was appointed the founding Director and Head of the National Mathematical Centre (NMC) at Abuja. In 1996 Professor Ezeilo went to University of Botswana for one year as a visiting Professor of Mathematics. Thereafter, in 1997 he took up a similar post at the University of Swaziland, until his final return to Nigeria in 2001. Not one to stay away from Mathematics and the academia for too long, JOC as he was popularly known, took up a position of Professor of Mathematics at the budding Ebonyi State University Abakaliki an a part-time basis in 2002, remaining there until his final retirement in 2009.Scott Williams gives the following summary of Ezeilo's mathematical contributions :-
James Ezeilo's early research dealt mainly with the problem of stability, boundedness, and convergence of solutions of third order ordinary differential equations. Apart from extending known results and techniques to higher order equations, the main thrust of his work was the construction of Lyapunov-like functions, which he did elegantly and used to study the qualative properties of solutions. In addition he was a pioneer in the use of Leray-Schauder degree type arguments to obtain existence results for periodic solutions of ordinary differential equations.Among his last papers to be published we mention Some third order differential equations in physics which he co-authored with Alexander Animalu, Non resonant oscillations for some fourth order differential equations (Part I in 1999, Part II in 2001, Part III in 1999), Periodic boundary value problems for some fourth order differential equations (2000), and Further instability theorems for some fourth order differential equations (2000).
The obituaries  and  are largely identical but as each contains a little information not in the other we have produced versions of both articles.
For the Bayero University, Kano, obituary, see THIS LINK and for the Nigerian Guardian obituary, see THIS LINK.
In  Ezeilo's memberships and honours are listed: member, London Mathematical Society; member, American Mathematical Society; member, Science Association of Nigeria; member, Nigerian Council for Science and Technology (1970-75); member, Mathematical Association of Nigeria; President, Mathematical Association of Nigeria (1972-74); member, Nigerian Mathematical Association; President, Nigerian Mathematical Association (1984); foundation fellow, Nigerian Academy of Science; fellow, Third World Academy of Sciences (1986-2013); fellow, African Academy of Sciences (1988-2013); fellow, Mathematical Association of Nigeria (1988-2013); chairman, Projects Development Agency (1970-74); awarded Commander of the Order of the Niger (1979); honorary D.Sc., University of Maiduguri (February 1989); honorary D.Tech., University of Science and Technology, Akure (1995); and honorary D.Sc., University of Nigeria, Nsukka (1996).
The Who's Who in Nigeria entry  gives Ezeilo's hobby as reading.
Following Ezeilo's death in 2013, the Edward Bouchet Abdus Salam Institute gave this tribute :-
The Edward Bouchet Abdus Salam Institute extends its heart-felt condolences to the family, friends, and colleagues of Founding Council Member Professor James Okoye Chukwuka Ezeilo who passed away in January of 2013. Professor Ezeilo was a very animated, enterprising, philosophical but pragmatic man with plenty of ideas. He was a brilliant mathematician and fun to be around and will be greatly missed by all who knew him. We, the members of the Edward Bouchet Abdus Salam Institute, are deeply saddened by his death.
Article by: J J O'Connor and E F Robertson