Ernst Casimir II of Ysenburg and Büdingen^{[citation needed]} (14 December 1806, Büdingen^{[citation needed]} – 16 February 1861, Büdingen^{[citation needed]}) was the second^{[citation needed]} Prince of Ysenburg and Büdingen. Ernst Casimir was the eldest son and second eldest child of Ernst Casimir I, 1st Prince of Ysenburg and Büdingen and his wife Countess Ferdinande of Erbach-Schönberg.^{[citation needed]}

You can help expand this article with text translated from the corresponding article in German. (December 2009) Click [show] for important translation instructions. View a machine-translated version of the German article. Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia. Consider adding a topic to this template: there are already 9,127 articles in the main category, and specifying|topic= will aid in categorization. Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article. You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing German Wikipedia article at [[:de:Ernst Casimir II. zu Ysenburg und Büdingen]]; see its history for attribution. You may also add the template {{Translated|de|Ernst Casimir II. zu Ysenburg und Büdingen}} to the talk page. For more guidance, see Wikipedia:Translation.

At the age of 12, Ernst Casimir attended the Royal Prussian Pädagogium in Halle. After passing Maturum in 1826, Ernst Casimir studied first at the University of Giessen and later at the Berlin College of History and Archeology. To learn the French language, he held temporarily studied in Basel and Geneva. Ernst Casimir also served for several years in the Imperial and Royal Army of the Austrian Empire. On 1 November 1848, succeeded to the title of Prince of Ysenburg and Büdingen upon the abdication of his father.

Ernst Casimir married Countess Thekla of Erbach-Fürstenau, fourth eldest daughter of Albrecht, Count of Erbach-Fürstenau and his wife Princess Emilie of Hohenlohe-Neuenstein-Ingelfingen, on 8 September 1836 in Beerfelden.^{[citation needed]} Ernst Casimir and Thekla had five children:^{[citation needed]}

• Bruno Casimir Albert Emil Ferdinand, 3rd Prince of Ysenburg and Büdingen (born 14 June 1837 in Büdingen; died 26 January 1906 in Büdingen)^{[citation needed]}

∞ Princess Mathilde of Solms-Hohensolms-Lich (1842–1867) on 31 July 1862 in Lich, had two issue

∞ Countess Bertha of Castell-Rüdenhausen (1845–1927) on 30 September 1869 in Rüdenhausen, had eight issue

• Prince Adalbert of Ysenburg and Büdingen (born 17 February 1839 in Büdingen; died 29 August 1885 in Kennenberg)^{[citation needed]}

∞ Princess Alexandra of Ysenburg and Büdingen in Wächtersbach (1855–1932) on 18 November 1875 in Wächtersbach, no issue

• Princess Emma Ferdinande Emilie of Ysenburg and Büdingen (born 23 February 1841 in Büdingen; died 22 April 1926 in Rüdenhausen)^{[citation needed]}

∞ Wolfgang, Prince of Castell-Rüdenhausen (1830–1913) on 17 May 1859 in Büdingen, had nine issue

• Princess Agnes Marie Luitgarde of Ysenburg and Büdingen (born 20 March 1843 in Büdingen; died 17 October 1912 in Meerholz)^{[citation needed]}

∞ Karl, Count of Ysenburg and Büdingen in Meerholz (1819–1900) on 21 November 1865 in Büdingen, had five issue, among which:

1. Count Friedrich of Ysenburg and Büdingen in Meerholz, who married Princess Marie Reuss of Greiz (daughter of Heinrich XX, Prince Reuss of Greiz), no issue
2. Countess Gisela of Ysenburg and Büdingen in Meerholz, who married Prince Friedrich Wilhelm of Lippe (son of Julius, Count of Lippe-Biesterfeld) and had a daughter, Princess Calixta of Lippe

• Prince Lothar of Ysenburg and Büdingen (born 27 September 1851 in Büdingen; died 23 February 1888 in Wiesbaden)^{[citation needed]}

∞ Countess Jacqueline Worbert of Wassenaer-Starrenburg (1853–1930) on 19 August 1875 in Almelo, no issue