Scholar of OT and Syriac, professor of OT and Semitic studies at the Catholic University of Nijmegen (now: Radboud University), The Netherlands, from 1951 to 1979; Dominican Father; and Chorbishop of the Syriac Catholic Church since 1963.
Even though Syriac was not always at the center of van der Ploeg’s academic work, he left some important publications in this field. Widely kown and used among Syr. scholars is his 1983 book on the Christians of St. Thomas and their Syr. mss. This focuses on a number of important libraries in Kerala and provides descriptions of the main Syr. mss., along with more general information on the religious, literary, and cultural history of the various Christian communities. To one of these mss., preserved in the library of the Malankara Catholic archbishop at Trivandrum, he devoted a follow-up publication, in which he edited, translated, and annotated a not otherwise known version of the Book of Judith (one of the deuterocanonical or apocryphal OT texts). A Festschrift was presented to him in 1982.