Corn silage refers to stalks, leaves and cobs of maize plants that remain in fields after the corn harvest. Commonly it is used as a cattle feed, but recently it has been more often used together with cattle manure in biofuel production in anaerobic co-digestion. In this work high-pressure and temperature extraction of phenolic compounds from corn silage was performed. Process parameters (temperature, T = 90 – 180 °C; extraction time, t = 40 – 120 min; liquid – solid ratio, 10 – 20 mL/g; and solvent concentration (10 – 90 % aqueous ethanol, v/v) were studied. Box-Bhenken design was used in order to obtain the maximal extractability of phenolic compounds (namely total phenolic compounds- TPC and total extractible proanthocyanidins - TPA) and the maximal antiradical power (ARP) of obtained extracts. Experimental results of TPC, TPA, and ARP of corn silage extracts were in the range from 10.01 – 72.43 mgGallicAcid Equivalent/gdrybiomass, 0.27 – 3.21 mg/gdrybiomass and 1.25 – 16.76 mgDPPH/mLextract, respectively. Statistical results confirmed that temperature was the most significant factor affecting the observed responses (p < 0.05). Optimal extraction conditions for TPA and ARP were achieved at 180 °C, 120 min using 65 % ethanol and L/S ratio 10 while optimal conditions for TPC were achieved at 180 °C, 120 min using 10 % ethanol and L/S ratio 20. The results of this study evidenced that extracts from corn silage can be a good source of antioxidant compounds which can be used for production of food, cosmetic and pharmaceutical products.