Abstract: In the present study, we attempted to produce in a laboratory scale high antioxidant activity extracts from echinoderm byproducts including green urchin (Strongylocentrotus droebachiensis) digestive tract and non-commercial grade gonads and Atlantic sea cucumber (Cucumaria frondosa) viscera by using Pressurized Liquid Extraction (PLE). We used deionised water, methanol, ethanol and isopropanol as extraction solvents. For each solvent, three extraction temperatures were tested successively, including 40, 60 and 80°C. Antioxidant activity was analysed using oxygen radical absorbance capacity assay (ORAC test). Results showed that first tests using 40°C extraction showed that ethanol and isopropanol were the best solvents to produce high antioxidant activity extracts from all the analyzed samples. When testing these two best solvents with higher temperatures (60 and 80°C) we observed ORAC values (3617-10148 μmol TE g-1 extract) generally better than 40°C-extracts (3463-8629 μmol TE g-1) though differences were not necessary statistically significant (p = 0.03-0.82). Linear correlation were observed between ORAC values and sample contents in α-tocopherol (R2 = 0.53), total carotenoids (R2 = 0.62) and total phenols (R2 = 0.73). This suggests those antioxidant potentials partly contributed to the observed ORAC responses but other compounds might be also involved. Present results showed that PLE improved antioxidant activity of echinoderm extracts up to 10 folds, compared to simple overnight stirring methods. In addition, it is observed from present results that PLE is suitable to produce high antioxidant activity echinoderm extracts, with ORAC values that might be comparable to, if not better than, some commercial antioxidant natural ingredients.