In the course of this graduation thesis we compared antioxidant capacity (AOC) and total phenolic compounds (TP) in green tea and matcha tea. We have examined how different methods of preparing tea infusions affect AOC and TP. The basic tea infusion was prepared with 1.6 g tea sample and 1 dL of tap water at 70 °C and we extracted samples for 3 minutes. Then we changed the parameters of tea preparation and compared AOC and TP of such samples with basic tea infusions. AOC of the samples was determined by DPPH• assay and TP were determined by Folin-Ciocalteu method. We have found that some methods of preparing a tea infusion have a significant effect on the AOC and TP in the infusions. We have determined that longer extraction time has a positive effect on both the TP content and the AOC of infusions. A higher temperature and a lower volume of water both have a positive effect on the content of TP and AOC in green tea infusions and on the AOC of matcha tea infusion, but have a negative effect on the content of TP in matcha tea infusion. The prolonged time after preparation of the infusions has no specific effect on the content of TP and AOC of infusions, and the use of distilled water has a small, but positive effect on most samples. Based on the overall results of all the analyzes in the preparation of tea infusions, it can be concluded that matcha tea infusions have the highest AOC and the highest content of TP, and that the AOU value and the content of SF are easily increased by extending the extraction time or increasing the water temperature in preparing green tea infusions.