Infusion-induced changes in the phenolics, antioxidant and colour propeties of St John's wort (genus, Hypericum; specie, Hypericum perforatum L.) teas were studied for the first time. SJW teas prepared as three different infusions and coded as three (3 min), six (6 min) and twelve minutes (12 min). Investigation of phenolic compounds were performed by LC-DAD-ESI-MS/MS. A total of 18 phenolics including six chlorogenic acids, three phenolic acids, seven flavonoids and two naphtodianthrones were detected. It is worth noting that the phenolic profiles of St John's wort teas were similar. However, the quantities of phenolic compounds individually and totally changed significantly for different infusion times. The highest total concentration was detected in 12 min (60.03 mg/L), followed by 6 min (54.81 mg/L) and 3 min (33.07 mg/L). The main difference for different infusion times was the hyperoside found as the most abundant phenolic only in 3 min samples. However, for 6 min and 12 minin infusions, chlorogenic acid was the most dominant phenolic compound. Similar to phenolics, antioxidant capacity of tea infusions showed an increasing trend with the extension of infusion time.