Kemeny was born in Budapest and immigrated to the United States in the late 1800's and lived in various cities (New York, Philadelphia and Chicago). He returned to Budapest in the early 1900's. While in the US he worked for the Pennsylvania Railroad in 1893 and at the same time edited and published the American Chess Weekly in Philadelphia and went on to edit a chess column in the Philadelphia Public Ledger and in the North American.
During the mid-1890s, Kemeny was one of the strongest players in the US. He took 2nd at Skaneateles 1891, lost a match to James Hanham (4–5) at New York 1891, and won at Skaneateles 1892. He also won the 1892-93 Franklin Chess Club championship tournaments as well as the Championship of Philadelphia, the nation’s second strongest chess metropolis, with a score of 14–4, a full point over Walter Penn Shipley. The next Franklin and city championship, that of 1893-94, however, showed Kemeny crushing his opposition with a score of 23–1, a full three points ahead of Mordecai Morgan, and four and a half points ahead of Hermann G. Voigt. In 1896, he had challenged Jackson W. Showalter, the U.S. Champion, to a match, which Kemeny lost, with the final score of +4 –7 =4.
He tied for 4-5th at Philadelphia 1898, shared 1st at Philadelphia 1899-1900, took 3rd at Philadelphia 1900-1901, and took 4th at St. Louis 1904 (the 7th American Chess Congress which was won by Marshall.
Between January and July 1897, he published correspondence chess games in the Philadelphia Public Ledger. In 1903 Kemeny went to Monte Carlo to report the Monte Carlo tournament for the North American. He published at Philadelphia for one year a weekly entitled the American Chess Weekly. This paper contained a full account of the Monte Carlo Tournament of 1903.
As strong a player as Kemeny was, he was best known for his annotations. The American Chess Magazine stated that "not since the withdrawal of Mr. Steinitz from the New York Tribune has the analysis of games been conducted in so complete and entertaining a style as Mr. Kemeny presents them."
Although not a correspondence player himself he appreciated correspondence play and gave a great deal of attention to correspondence chess in the Ledger.
Kemeny knew correspondence players studied positions in detail and in general conduct games at a higher level than otherwise would have been possible. In the Ledger for January 15, 1897 he wrote that "in correspondence play, where three days time is given to each move, high grade chess may be justly expected, but such flawless play in a complicated position, as exhibited by Mr. Ferris in the present contest, must be regarded as a rare occurrence."
The Continental Correspondence Tournament began modern correspondence tournament play in the United States. Seventy players began the tournament, which was conducted first in sections in a Preliminary Round followed by a Final Round. Shipley wrote that the tournament included "many of the best-known players of this country," and "was the largest and strongest Correspondence Tournament ever inaugurated up to that date this side of the water."
Kemeny kept up close watch on chess developments in Hungary, especially the first correspondence tournament to be held in Hungary and elaborated on his views on correspondence chess: "Chess by correspondence has of late become popular, and, though it requires considerable time to play a game, the result, as a rule, proves satisfactory to the contestants. Errors and oversights are minimized and in the majority of cases the game is won on its merits. Correspondence play especially benefits those who do not reside in the large cities and have, therefore, but few chances to meet opponents of equal strength. But the best feature of correspondence play is the quality of chess it produces. Ample time being given, the contestants are enabled to penetrate the position much deeper, and very often players of average strength conduct a correspondence game in a way that would do credit to a master."
He returned to his native homeland in the first decade of the 20th century, where he died in 1925.