The Monastery of Xeropotamou is one of the oldest monasteries on Mt. Athos, located inland from the southwest coast of the peninsula. Its origins are shrouded in legend and confusion; modern scholars place its foundation during the reign of Constantine VII. Xeropotamou (Enpororimov) was in existence by 956 when it received a grant of land from a certain protospatharios John. At this time it was dedicated to St. Nikephoros. The monks of Xeropotamou attribute its foundation to Paul Xeropotamites, who is known to have been on Athos in 958, but this claim must be treated with caution. It is possible that he was founder of the small Athonite monastery of St. Paul, which also bore the name tou Xeropotamou in the 10th and 11th centuries.
In the early 13th C. the church at Xeropotamou was restored and dedicated to the Forty Martyrs. Andmnikos II was also a benefactor of the monastery. By the late 14th century Xeropotamou held third place in the Athonite hierarchy. The present monastic complex dates from the 18th century or later. Its library contains approximately 40 manuscripts of Byzantine date, while its archives preserve 30 Greek documents dating between 956 and r445, including a series of six early 14th-century praktika for the theme of Thessaloniki, esp. Chalkidike. The monastery's most precious possession is a 14th-century steatite paten known as the "cup of Pulcheria."
Oxford Dictionary of Byzantium