BACKGROUND: The objective of this work was to assess the influence of propane pre-treatment on the esterification activities of two non-commercial lipases from Penicillium simplicissimum and Aspergillus parasiticus in the lyophilized and immobilized forms, evaluating the effect of pressure, exposure time and depressurization rate on the lipase activity by a full 2(3) experimental design. RESULTS: For both lyophilized and immobilized lipases from all sources evaluated, enhancement in residual activities after incubation in pressurized propane was observed, under several experimental conditions. The highest increment (427%) occurred with the lyophilized enzyme from P. simplicissimum was maintained pressurized at 30 bar for 1 h and then depressurized at the fastest rate (20 bar min(-1)). CONCLUSION: The enzyme activity changes significantly depending on the enzyme source, its presentation form, and the experimental pre-treatment conditions investigated, such as exposure time, depressurization rate and pressure. The results obtained here can contribute as a basis for the selection of appropriate operational conditions, so that these catalysts can be applied in biotransformation reactions. (C) 2010 Society of Chemical Industry