This contribution deals with experimental corrosion tests carried out on the weathering steel railway bridge in Prague. The basic specific property of the weathering steel is an ability to create in favourable environment a protective patina layer on its surface. Since 1968 weathering steel is used under the name “Atmofix” in the Czech Republic and can be used as a standard structural material without any corrosion protection. The weathering steel Atmofix is mostly used for bridge structures and lattice transmission towers. Some of these constructions built in the Czech Republic have been assessed and inspected in the last few years. Authors of this paper developed a new methodology of nondestructive experimental testing of corrosion processes. Testing specimens are installed on typical surfaces of steel bridges in such a way to simulate real conditions of the examined surface. This paper describes results of corrosion tests (thickness of corrosion products, corrosion losses and X-Ray analysis) after one-year exposure, correlation factor and dependence of location.