Summary The biological detoxification of mycotoxins, including deoxynivalenol (DON), represents a very promising approach to address the challenging problem of cereal grain contamination. The recent discovery of Devosia mutans 17‐2‐E‐8 (Devosia spp. 17‐2‐E‐8), a bacterial isolate capable of transforming DON to the non‐toxic stereoisomer 3‐epi‐deoxynivalenol, along with earlier reports of bacterial species capable of oxidizing DON to 3‐keto‐DON, has generated interest in the possible mechanism and enzyme(s) involved. An understanding of these details could pave the way for novel strategies to manage this widely present toxin. It was previously shown that DON epimerization proceeds through a two‐step biocatalysis. Significantly, this report describes the identification of the first enzymatic step in this pathway. The enzyme, a dehydrogenase responsible for the selective oxidation of DON at the C3 position, was shown to readily convert DON to 3‐keto‐DON, a less toxic intermediate in the DON epimerization pathway. Furthermore, this study provides insights into the PQQ dependence of the enzyme. This enzyme may be part of a feasible strategy for DON mitigation within the near future. This report describes the discovery of a dehydrogenase responsible for the selective oxidation of mycotoxin deoxynivalenol (DON) at the C3 position. The enzyme was shown to readily convert DON to 3‐keto‐DON, a less toxic intermediate in the DON epimerization pathway. This enzyme may be part of a feasible strategy for DON mitigation within the near future.