He is the author of more than 15 monographs, 50 papers and studies. His researches are in the fields of Bulgarian Renaissance, Russian history, history of the Ottoman Empire, the Eastern Question and the National Idea. In 1983 he defended a doctoral thesis on "The Church struggles in Thrace until 1878" and in 2003 he acquired degree of Doctor of historical sciences after defending a thesis on "Dr. Stoyan Chomakov (1819-1893). Life, deed, descendants”. He is a member of the editorial board of the Bulgarian Historical Review. He has completed scientific specializations at the Russian Academy of Sciences, the British Academy and the National Center for Scientific Research, France. Todev also participated in numerous research projects and forums. "