HIGHLANDS, N.J., June 10 - Fletcher Pratt, historian, scholar and writer, died today of cancer in Monmouth Memorial Hospital, Long Branch. He was 59 years old.

The author of more than 50 books, Mr. Pratt ranged far in his subject-matter. He wrote with skill, familiarity and competence on matters as diverse as history and science-fiction, cryptography and the culinary arts, biography and news commentary.

A scrupulous scholar, he wrote with "enormous gusto and enthusiasm," as one reviewer noted. His style generally was lively, terse and witty. Still another critic, observed, Mr. Pratt "never learned that history is dead."

So it was that there was as much vividness, information and excitement in The Third King, the story of a fourteenth-century Danish ruler, or the Road to Empira series, dealing with Napoleon, as there was in War for the World, the story of World War II.

Although at home in any era, Mr. Pratt earned a reputation as a naval historian. Among his books in this field were Preble's Boys, tracing the roots of early American sea power. The Monitor and the Merrimac, The Navy's War, and Fleet Against Japan.

Ordeal by Fire Praised

His Ordeal By Fire, a history, of the Civil War, won wide acclaim in the Nineteen Thirties. It since has been enlarged upon in the light of new historical facts.

Yet when Mr. Pratt turned to other fields, he won acceptance almost as readily. He had a large following in the science-fiction field, where such works as Double Jeopardy and The Blue Star had big sales. The Government killed publication of a second edition of his book Secret and Urgent, dealing with codes when World War II began. His reputation as an epicure grew when he wrote A Man and His Meals in 1947 with Robeson Bailey.

Mr. Pratt even essayed straight fiction in writing a novel, The Well of the Unicorn, under the name George V. Flecther.

Typical of his achievement as a scholar was his mastering of the Icelandic sagas in the original (he found two extant translation most unsatisfactory) and his translation of foreign works such as H. J. Duteil's The Great American Parade from the French.

A wisp of a man who wore a thin, reddish beard, Mr. Pratt affected shirts of bright hues. He would have three or four books in the writing at one time, often on widely differing subjects, but he religiously closed shop each day at 5 P.M. and proceeded to relax.

Wrote for The Post

Because he was an acknowledged authority on military affairs, he returned to newspaper work during World War II as military expert for The New York Post. Before coming to New York in 1920, he had worked at The Buffalo Courier Express. He turned to writing for a living in 1923.

His career was all the more remarkable in that he was very largely self-educated. Buffalo-born, Mr. Pratt attended Hobart College for one year and more than a dozen years later spent another two years at the University of Paris.

As a young man, he tried his hand as a professional boxer. He weighed in at 105 pounds in those days, which made him small even in the flyweight class, where there is a 112-pound limit.

For many years, Mr. Pratt was a member of the staff of the Bread Loaf Writers Conference, conducted by Middlebury College in Vermont. He was a former president of the Author's Club and a member of the Baker Street Irregulars, The American Rock Society and the Trap Door Spiders.

A number of his books were illustrated by his wife, Inga Stephens, who suvives.