The superplastie forming potential of two fine-grained 5083 aluminum alloys were studied under biaxial tension using apneumatic bulge test. Experiments were performed at temperatures ranging from 475 to 525℃ with three different strain pathsranging from equi-biaxial to approaching plane strain. The shape of the forming limited diagram(FLD) is found to be significantlydifferent from FLDs commonly used in room temperature stamping. The effects of temperature on final thickness distribution, domeheight and cavitation were investigated for the case of equi-biaxial stretching. Increasing temperature in free bulge forming canimprove the thickness distribution of final parts but have no significant effect on dome height. The results indicate that determinationof forming limits in SPF cannot be represented with a simple FLD and additional metrics such as external thinning and internalcavitation needed to determine the SPF potential of a material.