Adam Frans Jules Armand, Count van der Duyn, lord of Maasdam and 's-Gravenmoer (13 April 1771 – 19 September 1848) was a Dutch officer and politician.

However, Van de Duyn was quite enlightened and didn't belong to reactionary wing of the Orange party.

He rented the Castle of IJsselstein and lived there with his wife Maria Baroness van der Capellen, who he had married in 1799.

He joined the circle of conspirators around Gijsbert Karel van Hogendorp who were planning an uprising against the French occupators.

As a nobleman (predicate: Jonkheer, squire), he was entitled to join the Ridderschap, the College of Knights, of South Holland.

In 1848 the King appointed Van der Duyn a member of the Senate in order to secure a majority for the constitutional revisions.