The CVD Fe/Mo/supporting matrix (borosilicate molecular sieve, ZSM-5 or silicalite) was studied for gas-phase oxygen oxidation of p-xylene. The partially deboronated borosilicate molecular sieve matrix (DBH) played a unique role for the selective aldehyde synthesis. Terephthaldehyde was produced over CVD Fe/Mo/DBH, while disproportionation of p-xylene became predominant over CVD Fe/Mo/ZSM-5. The CVD Fe/Mo/silicalite exhibited relatively low activity and poor aldehyde selectivity.