The Diocese of Alcalá de Henares (Latin: Compluten(sis)) is a Latin Church ecclesiastical territory or diocese of the Catholic Church in Spain.

The diocese is a suffragan in the ecclesiastical province of the metropolitan Archdiocese of Madrid.

An ancient diocese of Complutum (the current Alcala de Henares) was founded in the 4th or 5th century but it was abolished under the Muslim government (8th–11th century) and not restored by the Christian Kings and its territory given to the Archdiocese of Toledo.

The diocese has a pop-rock group of Catholic music called The Voice of the Desert that is made up of three diocesan priests and four laymen.

This article about a Roman Catholic diocese in Spain is a stub.