The objective of this experiment was to determine the effectiveness of a chemical additive (SF; 20% sodium benzoate, 10% potassium sorbate, and 5% sodium nitrite) from Salinity (Gothenburg, Sweden) on improving aerobic stability of short-term ensiled corn silage. Whole plant corn was harvested at 39% DM, chopped, and untreated (CTRL), or treated with SF2 (2 L/t) or SF3 (3 L/t). Four replicated silos (7.5 L) were packed (224 kg of DM/m³) and opened after 1, 2, 4 and 46 d of ensiling. Untreated and SF2 ensiled for 46 d were analyzed after 48, 96, and 240 h of aerobic exposure. Silages were analyzed for microbial population, fermentation profile, and aerobic stability (h before a 2°C increase above baseline after exposure to air at 22°C). Data were analyzed by ANOVA as a factorial arrangement of treatments. After only 1 d of ensiling, SF2 was stable for 224 h and SF3 for 240 h, while CTRL was stable for 32 h. At d 2, 4 and 46 both SF2 and SF3 were stable for more than 240 h, while CTRL spoiled after 57, 81 and 117 h, respectively. Numbers of yeasts were similar among all treatments from 1 to 4 d. Only at d 46, there were fewer yeasts (P < 0.05) in treated silages (1.14 log cfu/g fresh weight) compared with CTRL (3.22). Concentrations of ethanol were the same among treatments at all openings. On silages ensiled for 46 d, at 48 and 96 h after aerobic exposure, no differences in pH were observed among treatments. However, at 240 h of aerobic exposure, CTRL pH was higher (P < 0.05) than SF2 (5.40 vs. 3.66). Numbers of yeasts were lower (P < 0.05) at all aerobic sampling time points and mold counts were lower (P < 0.05) after 240 h for SF2 compared with CTRL. These findings suggest that the additive is not immediately fungicidal, but its fungistatic effects apparently alter the metabolism of yeasts sufficiently enough to cause substantial improvements in aerobic stability. As the improvement on aerobic stability was observed as soon as after 1 d of ensiling, this additive might be useful for producers who cannot wait several weeks for silage to cure and that must feed out silage immediately or very soon after harvest.