His father, János Mogyoróssy (1771-1844), was the town councillor for several years, then he was the chief constable of the town in 1815. His mother, Ilona Vutsák, was also of noble ancestry. His birthplace was the house in the centre of Gyula, opposite the Roman Catholic Parish Church. (Today there is a square in place of the house.) Young Mogyoróssy started his studies in Gyula, and then continued in Arad, Timisoara and in Eger. From his childhood he was fond of drawing and painting. While studying in Timisoara, he had the opportunity to improve his knowledge in this area in János Schütz’s drawing classes. His teacher usually gave him the tasks of making castle fortification and strategic maps which made young Mogyoróssy interested in Hungarian history. This effect was enhanced as he could use his uncle, Ambrus Korneli’s (holdmézesi Ambrus Kornély /1776-1834/ judge of the County Court, chief cashier) library and his certificates at his pleasure, he could also discuss his thoughts with him. These effects „lit an inextinguishable fire in Mogyoróssy for history”. He often stayed in Pest where he was a regular visitor of the National Museum, and always went to József Eggenberger bookkeeper’s shop. He managed to get in touch with the celebrated writers and scientists of the 1820s and1830s who also affected his way of thinking (e.g. József Bajza, Károly Kisfaludy, István Kultsár, István Horváth, Gábor Döbrentey, etc.).

He read literal arts at Eger Archbishopric Lyceum and at the Royal Academy of Oradea until the end of the 1826-1827 terms. He was not able to continue his law studies as he ran out of the money his old parents saved for his studies. Therefore, from the end of 1827 János Mogyoróssy was a clerk of Békés county, he also handled the legal documents of count Ferenc Wenckheim’s estate in Gyula. In his free time he also turned his attention to his law studies, then he took a successful private exam, and from October 1828 he entered the service of the Gyula estate as the person who “speaks German, is able to write and draft” (he was employed as manor court notary), but he was also count Ferenc Wenckheim’s secretary for a while. At the end of 1832 he was appointed overseer of the Gyula estate. This year he married Anna Pecz (Imre Pecz /Petz, Pech/ the Vésztő estate granary clerk‘s daughter), and they had six children. Mogyoróssy’s livelihood became firm, his assets increased, which was indicated by the 56 acres of estate he bought from his earnings. Having this land made it possible for him to immerse in archaeology, and to collect antiquities. On his estate - on three acres – he planted and improved fruit trees, so encouraged planting of fruit trees in Gyula.

He first donated books in 1836. He was appointed bursar in 1846 and was trusted to take care of the archives of the count’s family in Gyula. As he handled many documents, he started to collect materials for some of his history related works. He was captain of the infantry national guard in Gyula in 1848. After the repression of the War of Independence he continued his job; then, in 1865 – after almost 40 years of service - he retired. His wife died in 1866, this blow made him work on his researches more intensively, and he actively participated in public affairs. János Mogyoróssy donated another collection of books and antiquities in 1868 to his beloved town and the future generations. Through this, he laid down the foundations of the town museum and library in Gyula. In 1874 Mogyoróssy with the participation of several celebrated people of the county established the Békés County Archeological and Culture-historical Society. This society supported the Békés County Museum that, in accordance with the customs of the time, also incorporated the library donated by Mogyoróssy. János Mogyoróssy took active part in the work of the society, and accepted the museum director’s post. He worked enthusiastically and gladly on the post almost until his death. The man, to whom the present inhabitants of the town can thank – among others – the foundation of the museum and the library, closed his eyes forever on 10 May 1893. The town library adopted its founder’s name in 1968.

1. Gyula hajdan és most történeti és statisztikai vázlatokban. (Gyula in olden times and now through historical and statistical drafts.) Gyula, 1858.

2. A Wenckheimi Hund család eredete és ivadékai Magyarhonban. (The origin and ancestors of the Hund family of Wenckheim on Hungarian soil.) Gyula, 1864. [Alternative title: Wenckheim-codex]

3. Gyulai határkő. (Merestone of Gyula.) In: Archeological Advisor, 1871. 5. [Analyses the inscription of the XVII^th century merestone found on the Boulevard.]

4. Gyulai lelet. (Findings in Gyula.) In: Archeological Advisor, 1871. 5. [Writes about his own excavations that he did south of the Calvary.]

5. Két gyulai lelet. (Two findings in Gyula.) In: Archeological Bulletin. 1871. 8. [Writes about the findigs at Szent-Benedek in 1867.]

6. Értekezése Mogyoróssy Jánosnak a hajdankori előszázadokban keletkezett magyar feliratú gyulai határkőről. (János Mogyoróssy’s essay about the merestone of Gyula with Hungarian inscription, which occurred in the previous centuries of olden times.) Gyula, 1872.   

7. Üdvözlet Göndöcs Benedekhez. (Compliments to Benedek Göndöcs.) Gyula, 1874.