Kemeny's family settled in New York and John attended the George Washington High School in New York City. Kemeny entered Princeton in 1945, after becoming an American citizen, where he studied mathematics and philosophy. However he took a year off during his undergraduate course to work on the Manhattan Project in Los Alamos. His boss in Los Alamos was Richard Feynman and he also worked there with von Neumann.
Returning to Princeton in 1946, Kemeny worked as a research and teaching assistant and an instructor in mathematics even though he was still an undergraduate. He graduated with his B.A. in 1947, then worked for his doctorate under Alonzo Church's supervision. Kemeny was awarded his doctorate in 1949 for a dissertation entitled Type-Theory vs. Set-Theory. While a doctoral student he was appointed as Albert Einstein's mathematical assistant. Kemeny later wrote:-
People would ask - did you know enough physics to help Einstein? My standard line was: Einstein did not need help in physics. But contrary to popular belief, Einstein did need help in mathematics. By which I do not mean that he wasn't good at mathematics. He was very good at it, but he was not an up-to-date research level mathematician. His assistants were mathematicians for two reasons. First of all, in just ordinary calculations, anybody makes mistakes. There were many long calculations, deriving one formula from another to solve a differential equation. They go on forever. Any number of times we got the wrong answer. Sometimes one of us got the wrong answer, sometimes the other. The calculations were long enough that if you got the same answer at the end, you were confident. So he needed an assistant for that, and, frankly, I was more up-to-date in mathematics than he was.Kemeny spent two years on a postdoctoral fellowship granted by the Office for Naval research. In 1950 he married Jean Alexander; they had two children. He had continued to study both mathematics and philosophy and his first full-time teaching position, in 1951, was a philosophy appointment at Princeton. But Snell writes in :-
He was on his way to a traditional distinguished scholarly career as a promising young assistant professor at Princeton with a joint appointment in mathematics and philosophy when he decided instead to accept the challenge of developing a new mathematics department at a college which he had barely heard of and which was certainly not known as a centre of excellence in mathematics.So Kemeny was appointed to the Mathematics Department at Dartmouth in 1953 and, two years later, he became chairman of the Department. He held this post until 1967. He was president of Dartmouth between 1970 and 1981 and, in 1982, he returned to full-time teaching. In fact he never gave up teaching while he was president, he had made it a condition of taking the post.
Kemeny will be remembered by most people as the co-inventor of the BASIC (Beginners All-purpose Symbolic Instruction Code) computer language. It was in 1963 that Kemeny with Thomas Kurtz decided that they wanted to give students easy access to computing. Snell in  writes:-
Just as von Neumann realised that a computer that did only ordinary arithmetic operations could have extraordinary power, Kemeny realised that to make this power available to everyone, a programming language could and should be exceedingly simple. This led him to develop with Tom Kurtz the computer language BASIC ...Kemeny and Kurtz designed the first "time sharing" system so that many students could a single computer at the same time. BASIC was designed to allow students to write programs easily. The first BASIC program was run at Dartmouth at 2 am on 4 May 1964. In the following year the General Electric Company established the first commercial time sharing system based on what Kemeny and Kurtz had set up at Dartmouth. In 1967 the two co-inventors of BASIC published their book on the language BASIC programming.
A teaching innovation which Kemeny introduced was in developing a Finite Mathematics course including topics that are no surprise to us today: logic, probability and matrix algebra. It was designed because he was unhappy that mathematics (entirely calculus in first year courses at that time) was :-
...the only subject you can study for 14 years and not learn a single thing that has been done since 1800.Along with co-authors Laurie Snell and Oskar L Thompson from Dartmouth, Kemeny wrote a number of famous texts on finite mathematics. They wrote Introduction to finite mathematics (1957) which appeared in later versions aimed at social science students in 1960 and business students in 1962. They also wrote Finite mathematical structures (1959) which gave a more theoretical approach to the topic but included applications to electricity and engineering. Kemeny also wrote A philosopher looks at science (1959) and with Snell and Anthony Knapp from Cornell he wrote Denumerable Markov chains (1966).
Kemeny was well known outside mathematical circles however for, in 1979, President Jimmy Carter asked him to chair the commission investigating the Three Mile Island nuclear accident :-
The Kemeny Commission, as it came to be called, was very critical of the nuclear power industry and its federal regulators.Kemeny's character was painted by his wife:-
He liked science fiction, football games, shrimp, all kinds of puzzles, Agatha Christie, and solitude (for two). He did not enjoy socialising. Before he retired, John recognised only two flowers, the tulip and the rose, and two pieces of music, the 1812 Overture and Poor Little Buttercup. These last years he had time to enjoy Mozart, wildflowers, pileated woodpeckers, eclipses. Sometimes he liked just to sit still and think.Many awards and honours were bestowed on Kemeny such as election to the American Academy of Arts and Sciences (1967). He was given the New York Academy of Sciences Award in 1984, the Institute of Electrical Engineers Computer Medal in 1986 and the Louis Robinson Award on 1990. He received twenty honorary degrees.
Article by: J J O'Connor and E F Robertson