The most common materials for structures built in civil engineering and architecture are concrete and steel. In another type of engineering, properties of materials for structures are very different. For example, the space technology and the aeronautics use structures in which the lightness is the main property of the material. Under the perspective of the execution of very light structures it is presented the possibility of the design of frame articulated structures constituted by rigidizable bars inflated with air pressure. The main goal of this work is to characterize the strength behaviour of a single inflated bar with high pressure air. Mechanical tests in laboratory will show the response of an inflated bar under tension, compression and bending. At a long term, the behaviour of a single bar will assist to desing more complex frame structures made by the assembly of inflated bars.