Phenolic compounds in beer are derived from grains and hops during processing and production. Thus, the total phenolic content (TPC) of beer extracts, from selected Canadian and foreign commercial, and laboratory produced beers were examined and ranged from 3.72 ± 0.23 to 13.73 ± 0.49 mg GAE/100 mL beer. The total flavonoid content (TFC) of the same beer extracts varied from 0.82 ± 0.02 to 5.28 ± 0.04 mg CE/100 mL beer. Of particular interest were the hydroxycinnamic acids (HCAs) and derivatives in beer extracts because of their antioxidant properties. Main HCAs and a key derivative of ferulic acid, 4-vinylguaiacol (4-VG), were identified in beer extracts by high performance liquid chromatography (HPLC). Significant variations in TPC, TFC, HCAs and 4-VG content were observed among the beer extracts. Antioxidant activities of beer extracts, determined by radical scavenging and ferric-reducing assays, were positively correlated (p < 0.05) with TPC, TFC, and 4-VG but observed negative correlation with individual HCAs (p > 0.05). The positive correlation of 4-VG with ABTS radical cation scavenging and reducing power assays is reported first time. These findings suggest that phenolic compounds and a key derivative of the hydroxycinnamic acid, 4-VG, may have the protective role in the beer as an antioxidant. •Stir stick stout, a local beer, had the highest content of total phenolics and flavonoids.•The major hydroxycinnamic acids were identified and quantified by HPLC-DAD.•4-Vinylguaiacol, (4VG), a derivative of ferulic acid, was identified first time in Canadian beer.•A positive correlation was reported for the first time between 4-VG and radical scavenging assays.•Local Canadian beer showed higher and strong free radical scavenging activities.