Mistletoe is a traditional medicinal plant containing bioactive phenolic compounds with, for example, anti-cancer effects. We prepared extracts rich in phenolic compounds using a high-temperature batch extraction (HTBE) method. The mistletoes used in this study belonged to the genera Scurrula, Dendrophtoe and Macrosolen, which are typical plants in Indonesia. As a result of experiments regarding antioxidant activity measured by the ABTS method, along with polyphenolic profiles in each extract, we found an extract from S. oortiana showing a high antioxidant activity of 51 µmol TEAC/g extract as well as high content of phenolic compounds (289 mg GAE/g extract) among the mistletoe extracts obtained by HTBE. Candidate compounds responsible for the effect were quercetin 4′-O-β-glucopyranoside and gallic acid; other phenolic compounds such as catechin, epicatechin, rutin and quercetin partly contributed to the antioxidant effect of mistletoe extracts obtained by HTBE.