The present work was performed in order to investigate the effect of in situ immobilisation of commercial Aspergillus niger pectinase in rigid polyurethane foam (RFPU) on thermal stability. Pectinase (liquid, lyophilised, and immobilised) was incubated from 50 to 80 C. Residual activity data were fit to various kinetic models, which were rigorously evaluated by statistical and physical criteria. The first-order model provided the best fit to describe the thermal deactivation of pectinase. Immobilised pectinase exhibited higher thermal stability