• First reported reactor explosion in a new adipic acid synthesis route via nitric acid oxidation of n-hexane, highlighting overlooked thermal hazards.
• Increasing nitric acid concentration from 3.7 to 5.4 mol·L−1 drastically reduces thermal stability, with heat release exceeding the explosion threshold (1000 J·g−1).
• Maximum self-heat rate and pressure rise rate increase by at least 7-fold and 11-fold, respectively, leading to reactor pressure far beyond its rated limit.
• The PPL liner material was ruled out as a cause, emphasizing the critical role of process parameters in preventing similar incidents.