A bearded, muscular man sits draped in a deep red cloth, his body turned toward the viewer while his head rests on his right hand in a gesture of contemplation. He is surrounded by books, with one large open volume resting on his knee and another open book lying on the table before him, its pages illuminated by a strong, clear light from the left. To his left, a stack of closed books rises beside an hourglass and a bundle of papers, all rendered with careful attention to their textures and the play of light over their surfaces.

At his feet, a lion crouches, its head turned outward and its mane painted in rich, dark tones that contrast with the pale flesh of the figures above. The setting is an interior, with a window opening onto a blue sky and clouds behind the main figure, creating a sense of space and airiness that contrasts with the shadowed room. The composition is anchored by the diagonal sweep of the red drapery, which leads the viewer's gaze across the painting and unifies the various elements.

Rubens uses broad, energetic brushstrokes for the drapery and lion's mane, while the flesh of the figures is modeled with smooth, subtle transitions of light and shadow. The central figure's furrowed brow and intense gaze convey a mood of deep thought and study, while the cherubs and lion add symbolic and narrative layers to the scene. This is St. Jerome in his study, painted by Peter Paul Rubens between 1608 and 1609.

The painting is executed on panel, a support that allows for the fine detail and luminous color seen in the rendering of flesh, fabric, and sky. The presence of Jerome, the lion, the books, and the angelic figures connects the work to the iconography of Christian scholarship and contemplation. Peter Paul Rubens creates a dynamic and monumental composition, characteristic of his early seventeenth-century style.