The aim of this study was to evaluate the effect of chemical and microbiological additives on fermentation characteristics in com silage at 1, 3, 5, 10 and 90 days of ensiling. The following additives were used: commercial bacterial inoculant (2 g/t) containing homofermentative lactic acid bacteria Lactobacillus plantarum, Lactobacillus paracasei and Pediococcus pentosaceus, and chemical additive containing formic acid, propionic acid, ammonium formate and benzoic acid (4 1/t). Both additives positively influenced the fermentation process in corn silage. Their application resulted in a decreased pH in the treated compared to untreated silage at 1 day of ensiling (P