| Ducal House of Cadaval | |
| Parent House: | Braganza |
| Coat Of Arms: | Armes Ducs de Cadaval.jpg |
| Country: | Portugal |
| Titles: |
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| Founding Year: | 1648 |
| Founder: | Nuno Álvares Pereira de Melo, 4th Marquis of Ferreira |
| Current Head: | Diana Álvares Pereira de Melo, 11th Duchess of Cadaval |
| Estate: | Palace of the Dukes of Cadaval |
Duke of Cadaval is a title of Portuguese nobility. It was created on 26 April 1648 by King John IV of Portugal for his distant cousin, Dom Nuno Álvares Pereira de Melo (1638–1725), who was already 4th Marquis of Ferreira and 5th Count of Tentúgal.
The Dukes of Cadaval trace their origins to Dom Álvaro of Braganza, Lord of Tentúgal, Póvoa, Buarcos and Cadaval, fourth son of Dom Ferdinand I, 2nd Duke of Braganza. Dom Álvaro married Dona Filipa de Melo, the rich daughter and heiress of Rodrigo Afonso de Melo, 1st Count of Olivença.
The ducal family's name is Álvares Pereira de Melo.
Dom Nuno Álvares Pereira, the remarkable Constable of Portugal, is among their ancestors.
When Jaime Álvares Pereira de Melo, 10th Duke of Cadaval died in 2001, he left four daughters: two from his first (civil) marriage (with Antoinette Louise Schweisguth, ex-wife of René Durrieu, 4th Baron Durrieu), and two others from his second (religious) marriage (with Claudine Marguerite Marianne Tritz). Leadership of the house and its possessions was disputed by the elder daughters of each marriage:
Duarte Pio de Bragança, in the de jure capacity of Head of the historical Royal House of Portugal, recognized Diana Álvares Pereira de Melo as the 11th Duchess of Cadaval.
However, he also granted to her eldest half-sister, Rosalinda Álvares Pereira de Melo, the new title of Duchess of Cadaval-Hermès, because she is married to Hubert Guerrand-Hermès, the House of Hermès's heir. Dona Rosalinda also obtained both titles of Marquise of Ferreira and Countess of Tentúgal, historically allocated to the heir of the Duke of Cadaval. But Rosalinda (or her heirs) isn't the designated heir to the Duchy and the person to succeed her younger half sister as Duchess of Cadaval will be chosen by the Duke of Braganza at the time of the death of the current Duchess.
There is some controversy about the Cadaval-Hermès title, as effectively it constitutes a new creation since the inauguration of the republican regime in Portugal. The Republic abolished all titles of Portuguese nobility in 1910.