Eremo di Santa Caterina d'Alessandria, Hermitage church in Rio nell'Elba, Italy.

The Eremo di Santa Caterina d'Alessandria is a small Catholic hermitage in the Santa Caterina area of Rio nell'Elba. Its plain facade has two windows and a broken tympanum, with a squat bell tower above; a plaque beside one window records the 1973 restoration. Inside is a single nave with a trussed ceiling.

The hermitage probably dates to the Romanesque period and was enlarged and remodelled in 1634. Saint Paul of the Cross stayed and preached here during his time on Elba. A plaque beside one of the two facade windows records a restoration carried out in 1973.

The hermitage's origin is tied by tradition to a series of apparitions of Saint Catherine to a local boy; in memory of these, a festival is held every year on the Monday after Easter. Saint Paul of the Cross stayed and preached here during his time on Elba. The altarpiece, a painting of the mystical marriage of Saint Catherine attributed to Giovanni da San Giovanni, is now kept in the church of San Giacomo in Rio nell'Elba.

The site is reached by a marked footpath lined with cypress trees and Mediterranean plants, situated at about 260 meters elevation. Wear sturdy shoes because the route includes steep sections and winds through natural terrain.

The grounds contain the dei Semplici Gardens, dedicated to studying and protecting native plants found across the Tuscan Archipelago. This botanical collection lets visitors see the local plant life from all seven islands in one location.