ABSTRACT This work aimed to evaluate the thermostability of antioxidant (superoxide dismutase - SOD, catalase - CAT and ascorbate peroxidase - APX) and deteriorative (guaiacol peroxidase - G-POD, polyphenoloxidase - PPO, pectin-methylesterase - PME and polygalacturonase - PG) enzymes from soursop and cashew apple juices. Juices were prepared homogenizing ripe fruit pulps and submitting to different thermal treatments (55, 65, 75, 85 and 95°C) for different time period (1, 3, 5, 10, 15, 20 and 30 min) then enzymatic activities were evaluated. The treatments at 55°C for soursop juice and at 75°C for cashew apple juice presented the best results, considering the low residual activities for deteriorative enzymes and the retained activity of SOD. Our results suggest appropriate technological condition to thermal processing from soursop and cashew apple juice whereby ensuring quality beyond their functionality.