Historian, toponymist, archivist and academician.

He was born in Temesvár (today Timişoara, Romania). Initially his family name was Pesthy, but it was misspelled at the registry office. He went to gymnasium in Temesvár and to high-school in Szeged. His teachers noticed his talent very quickly – especially the philosopher Cyrill Horváth, the future university professor. He received a lot of support from his teachers. He returned to his home town where he worked at the headquarters of the commander of the army corps. In 1846 he got married with Mária Fiala. They had four sons and five daughters. As a young civil servant he took part in the political and cultural movements in Temesvár and in a short time he became one of the leadrs of the local Hungarians. This is a reason why after the war council proclaimed the state of emergency, Pesty was expelled from the fortress.

In April 1849 he went in Debrecen and offered his services to the Substitute Minister of War György Klapka, who was originary from Temesvár. He hired Pesty at the Department of Justice. During the war of independence he was in Buda, Arad, Lugos (today Lugoj, Romania), depending on where the fights were. After the defeat in Temesvár, he went to Turkey, to Vidin where he was exiled. He returned home because of his illness and his family was allowed to take care of him. But soon was taken to Pest to prison. He was released in February 1850. As soon as he arrived home he vent to Mehária (today Mehadia, Romania) for his belongings. He was suspected that he knew where the crown was, therefore he was arrested and taken to Orsova (today Orşova, Romania) where he had been tortured for six weeks. After it turned out that he was innocent, he was released and he could return to Temesvár. Here, he was appointed secretary of the chamber of commerce and industry. He had been working there until 1864. It was his mainly merit that in 1857 the economic society of Temes County was founded, which in short time was dissolved. In the same year he represented the chamber of commerce of Pest at a statistical congress in Vienna. In 1858 on the commander’s order he went to visit the mining towns in Krassó County (today Caraş County, Romania) to study mining industry.

In the second half of 1858 authorized the editing of an encyclopaedic paper, which was published under the name of Delejtű in July 23, 1861 in Pest. The paper had mainly scientific and economic articles. The secret goal of the paper was to prepare the way for the annexation of Banat county and Vojvodina back to Hungary. This was the reason why he received several warnings, the paper was distained several times, his house was searched through and her documents were confiscated. The new governor, General St. Quentin, who came after Coronin, arrested him and detained him in the fortress, but after the October Diploma was adopted, he had to release him at the end of October.

In these years he published Temesvár múltja (The Past of Temesvár, A tatárjárás korabeli magyar nádorokról (About the Palatines During the Tartar Invasion), Magyar helynevek (Hungarian Toponyms). In December 16, 1859 he was elected corresponding member of the Hungarian Academy of Science. In 1862 he held his inaugural speech entitled A templáriusok Magyarországon (The Templars in Hungary). In 1862 he was sent by the Chamber of Commerce to the international exposition in London, where he stayed for one month. From there he went to France, Belgium and Germany to gather experience.

The citizens of Temesvár appointed him mayor, but he refused the candidature. At the end of the year he represented Arad in Parliament and in 1876 Körmöczbánya. In the same year he became royal councillor. In 1864 the First Hungarian Industry Bank was founded, Pesty became its secretary and moved to Pest. It began a very successful period of scientific activities for him.

In 1867 he was authorized to found a historic newspaper Századok (Centuries). In 1867, together with Arnold Ipolyi and Mihály Horváth he founded the Hunagarian History Society. His other works were: A perdöntő bajvívások története Magyarországon (1865) (The History of the Decisive Duels in Hungary), A temesi bánság elnevezésének jogosulatlansága (The Unjustified Name of Banat) (1868). Between 1870 and 1885 he went through all the archives in Hungary. He managed to put together a collection of 100000 documents, originals and copies made by him. After this he published several other important works: A világtörténelem napjai (The Days of The World History) (1870), a Szörény vármegyei hajdani oláh kerületek (Szörény County’s Old Romanian Districts) (1877), a Brankovics György rác despota birtokviszonyai Magyarországon (The Serbian Despot, György Brankovics’s Estates in Hungary) and his work of three volumes entitled A Szörényi Bánság (Banat in Szörény)(1877-78). His most important works were: Az eltűnt régi vármegyék (The Counties That Do Not Exist Anymore) (1880) and the two volume work entitled A várispánságok története (The History of the Castles) (1882). In the same year he published his work in German entitled: Die Entstehung Croatiens, in which he analyzed without taking sides the relationship between Hungary and Croatia as he also did in his work entitled 100 politikai és történeti levél Horvátországról (100 Political and historical Letters from Croatia).

He became member of the Hungarian Academy of Sciences in 1877, in the meanwhile he became secretary of the 2nd department and the executive of the historical committe.

In 1868 he was asked to write the monography of Temes and Krassó counties (today Timiş and Caraş Counties, Romania). As a result he wrote Krassó vármegye története (The History of Krassó County) (1883-84). In the same year, the Committee of the Vatican Archives was founded in Hungary. One of its goals was to copy the Papal tenth list in Rome. Pesty was sent to Rome to copy the list, he spent there several months. His last and also important work was published in 1888, entitled Magyarország helynevei (The Locality Names in Hungary). For it he had gathered material from 1864. His work consisted of 67 volumes, out of which only one was published during his lifetime. He died on November 23, 1889 in Budapest. According to the National Széchényi Library his books of 67 volumes have been the most read works in the library.

In 2008 the Heti Új Szó magazine in Timisoara, as an acknowledgement of his achievements founded the Pesty Frigyes Commemorative Medallion.