Francisco de Moncada, 3rd Marquis of Aitona, stands before a plain brown backdrop, his figure turned slightly to the left while his gaze meets the viewer directly. He wears a dark, richly textured doublet adorned with rows of gold buttons and a broad white collar that frames his face, the light catching the crisp edges of the linen. His right hand clasps a black sash across his chest, while his left rests at his waist, fingers curled around the hilt of a sword, the knuckles rendered with subtle modeling.

The sitter’s face is illuminated with soft, even light, revealing the pale skin, carefully groomed mustache, and pointed beard, while the cheeks and forehead are painted with delicate, smooth brushwork. Behind him, a monumental stone column rises at the right edge of the canvas, its surface cool and grey, and above it appears an elaborate coat of arms in red, gold, and silver, signaling his noble status. The background is loosely painted, with warm brown tones and indistinct forms that push the figure forward, enhancing the sense of presence and authority.

The restrained color palette—dominated by blacks, whites, and earth tones—heightens the sitter’s dignity and the gravity of the occasion. Gold highlights on the buttons and the coat of arms catch the light, providing subtle accents amid the somber clothing. The paint surface shows van Dyck’s characteristic finesse, with smooth transitions in the flesh tones and crisp, controlled lines in the details of the costume and insignia.

A signature, 'A. Vandyck,' is visible on the stone base beneath the coat of arms, linking the painting unmistakably to its creator.