The Textus de Ecclesia Roffensi per Ernulphum episcopum (The Book of the Church of Rochester through Bishop Ernulf), usually referred to as the Textus Roffensis, is a mediaeval manuscript that consists of two separate manuscripts that were written between 1122 and 1124. It is catalogued as 'Rochester Cathedral Library, MS A.3.5' and is currently held in the Medway Studies Centre in Rochester, Kent. It is thought that the main text of both manuscripts was written by a single scribe, although the glosses to a Latin entry were made by a second hand.
A textus was a book with a decorated cover suitable to be kept in the church by the high altar. The term does not mean a text concerning Rochester Cathedral. A liber was a less decorated book, suitable only for the cloister. It is rare that a secular book is a textus, and the name given to the Textus Roffensis by the cathedral is considered indicative of the book's importance during the Middle Ages.
The two manuscripts were bound together in around 1300. The first part is a collection of documents which includes the Law of Æthelberht, attributed to Æthelberht of Kent (c. 560–616), and the 1100 coronation charter of Henry I of England. The Law of Æthelberht is the oldest surving English law code and the oldest Anglo-Saxon text in existence. The second part of the Textus Roffensis is the oldest of the Rochester Cathedral registers. The entire volume consists of 235 vellum leaves.
Over the centuries, the Textus Roffensis has been loaned, lost and recovered on several occasions and has been in the custody of a variety of different people and places: it is now held at the Medway Studies Centre in Rochester, Kent. The book was also submerged either in the River Thames or the River Medway for several hours after the ship transporting it sank. Water damage can be seen on a number of the pages.
The book was named 'Britain's Hidden Treasure' by the British Library, was the subject of a conference at the University of Kent in 2010.