Abstract: Numerous testing procedures have been developed in order to qualify adhesion of organic coatings used for protection of metallic surfaces against corrosion. This work deals with the development of a new test based on ultrasonic solicitation of samples of steel substrates coated with paint films which thickness are lying in a range of 20 to 40 um. The various steps of the design of the experimental equipment and the last improvements are described. The aims of the thesis are the characterisation of mechanical behaviour of the protective film under periodic solicitation in wet medium, the monitoring of the reliability of the manufacturer's process and to try to predict the durability of the manufactured products under tropical conditions. The various experiments point out that water takes an important part during the test. The experimental results collected on the various samples make evidence that mechanical properties depend on the water barrier effect and on the exposure time of the organic coating to the tropical conditions. It is finally demonstrated that the durability of the manufactured products can be related to morphological aspects of the damages types undergone by the samples during the test.