The author analyzes the works of Byzantine intellectual Demetrios Kydones (c.1324-c.1397) (Monody on the Fallen in Thessaloniki, his letters and orations) as a source on the history of the Zealot movement in Thessaloniki in the mid-14th century. The article examines the genre peculiarities of Kydones’ rhetorical writings, and the peculiarities of his style, as well as reveals some essential details of the Zealot uprising described in these sources. The textual analysis of Kydones’ Monody enables the author to adduce some additional arguments for a new dating of Nicolas Kabasilas' Discourse Concerning Illegal Acts of Officials Daringly Committed against Things Sacred.