Vapour phase corrosion inhibitors are nowadays one of most common methods of anticorrosion protection because of their high efficiency. Since the number of inhibitors available on the market is constantly growing, researches done in laboratory and realistic conditions, that study their efficiency and lifespan, play a really important role. In this research work, it has been shown how the development of a method for efficiency assessment of multimetal vapour phase inhibitors works on copper with the stimulation of chlorides and iodine that cause the corrosion itself. During the testing, the samples covered in VpCl-126®, a vapour phase inhibitor in a form of a protection film, were exposed to an aggressive environment. Samples were soaked in sodium chloride solution to provoke corrosion, whose concentration was optimized, in order to test the efficiency of inhibitors depending on the concentration of chloride ions in a closed system. Because of the produced results, there were also tests with different methods of soaking copper samples in chloride solution. In a test involving iodine, corrosion is caused by injecting the iodine solution into the closed system. Samples saturated with the inhibitor were compared to the samples without inhibitor in every test. The samples were visually evaluated, photographed by a digital microscope and analyzed on FTIR spectrometer. Received results have shown that VCl has higher efficiency in closed systems in which the vapour phase contains only water. VCl shows better efficiency at low concentrations of chlorides. There is a certain level of protection on samples exposed to inhibitors in the presence of iodine. Comparing both recieved results from chloride and iodine researches, VCI has shown lower efficiency in atmosphere rich with iodine. FTIR spectra showed different kinds of changes on the surface saturated by inhibitor contrary to an surface without inhibitor.