A new experimental setup, which allows for testing in an equi‐biaxial loading condition, has been developed and applied to investigate the fatigue behaviour of thin films. A load controlled cycling, performed at room temperature on flat specimens, reproduces the strain amplitude and mean strain in the film corresponding to a thermal cycling in a given temperature range. The setup is based on the ring‐on‐ring test, which has been successfully used in biaxial fracture testing of glass and ceramics, and includes an optical in‐situ failure detection system. The method is validated for specimens consisting in a gold film deposited on a polymer substrate.