Bromelain is an enzymatic complex obtained from pineapple (Ananas comosus) fruits and stem. Thermoseparation of bromelain by poly(ethylene oxide) (PEO)- poly(propylene oxide) (PPO)- poly(ethylene oxide) (PEO) block copolymers aqueous solutions was studied. Triblock copolymers with different EO percentages and different molecular mass were evaluated. Copolymer solutions at different pH values, buffer concentrations and copolymer concentrations were investigated. It was found that cloud point temperature increases as a function of %EO and decreases with copolymer molecular mass, copolymer concentration and buffer concentration. The results showed that all the studied factors influenced enzyme partition. The best conditions were copolymer with 10% EO and molecular mass of 2000 g/mol, temperature of 25 degrees C, copolymer concentration of 5% (w/w), pH 6.0 and salt concentration of 15 mM. Enzyme activity recovery around 79.5%, purification factor around 1.25 and activity partition coefficient around 1.4 were obtained.