FTIR product studies of the OH-radical-initiate oxidation of di-n-butoxymethane (DNBM) in the presence of NOx were performed in an indoor photoreactor and in the outdoor simulation chamber EUPHORE in Valencia, Spain. The reaction products observed in both reaction chambers were n-butoxymethyl formate (NBMF), propionaldeyhde, and di-ii-butyl carbonate (DNBC), In the indoor reactor yields for NBMF and propionaldeyhde of 77 +/- 15 and 78 +/- 16 mol % were obtained in the system DNBM/MeONO/NOx/air/hv and 88 +/- 18 and 69 +/- 14 mol % in the system DNBM/H2O2/NOx/air/hv, respectively. In the outdoor chamber, yields of 80 +/- 8 and 44 +/- 11 mol % were obtained after sunlight irradiation of a DNBM/NOx/HONO/air mixture. For di-n-butyl carbonate (DNBC), an upper limit of less than or equal to 10 mol % was estimated for both reaction chambers. In the indoor photoreactor small amounts of n-butyl formate (NBF) and n-butoxymethyl butyrate (NBMB) were also detected with upper limits of 3 mol % for each compound. Bimolecular rate coefficients for the reactions of NBMF and DNBC with OH radicals were determined in the indoor photoreactor using the relative rate technique. Values of k(OH+NBMF) = (8.00 +/- 0.91) x 10(-12) cm(3) s(-1) and k(OH+DNBC) = (7.07 +/- 1.64) x 10(-12) cm(3) s(-1) were obtained. NBMF was synthesized and authentic samples were used for calibration. A photochemical mechanism was developed to describe the OH-initiated degradation of di-n-butoxymethane (DNBM) in the presence of NOx. The reaction scheme was tested by comparison of computer box model calculations and experimental data. Experimentally obtained and modeled concentration-time profiles for selected reactants are in excellent agreement.