The use of composite materials has spread to different applications among which, those using thin sheet plates subjected to biaxial loads are commonly used in the car and aerospace industries. Hence, there is need of a reliable specimen to test these materials under biaxial loads. This reliability depends on measurements that are accurate and repeatable. Thus these measurements depend on the proper design of specimens. This paper reviews the development of cruciform specimens of carbon fibre composite materials and how the geometric shape has evolved. Based on this review, a new geometric shape is proposed. This improvement is based on numerical analysis of the specimen and tests results of experimental measurements carried out using a four piston rig in an orthogonal arrangement. Deformation is measured in the centre of the specimen using strain gauges. By obtaining the principal stresses, it was found that maximum stresses occur in the centre of the specimen.