The bulge test is a multi-dimensional test used to characterize the mechanical properties of sheet metal under biaxial tension. A major advantage of the bulge test over the more conventional uniaxial tensile test is that the stress-strain curve extends to the range of effective strain found in many forming processes. It is clamped in place and inflated with hydraulic pressure. This paper describes mechanical behaviour of a copolymer polypropylene (PPC7712) under bulge test. Special equipment has been used for deforming the thin circular specimen. The measurement of the strain and stress fields applied to the specimen during the test is provided by a highresolution 3D camera system based on the image correlation technique. The experimental obtained results were compared to Ranknin and Hill theoretical models.