The effect of polyolefin extensional rheology on the non-isothermal film blowing process stability and minimum achievable final film thickness has been investigated experimentally as well as theoretically utilizing variational principle model for the film blowing operation. It has been revealed experimentally as well as theoretically that the relationship between film blowing stability window size (and/or minimum achievable final film thickness) and the extensional strain hardening is non-monotonic in character for a given range of melt strengths, i.e. there is existence of the optimal values for both variables to reach maximum stability window size and/or the smallest minimum achievable final film thickness. (C) 2012 Elsevier Ltd. All rights reserved.