Quality assurance for corrosion testing involves validation of the testing apparatus and assessment of measurement uncertainty. Validation is actually the process of making the right decisions if a measurement procedure is suitable for a particular purpose, and the broadness of the validation experiment is important to investigate the behaviour of the method in all realistic operating conditions. The aim of this study was to investigate the problems related to the quality of the data obtained by measuring the rate of corrosion in salt spray and to analyse the need for evaluation of measurement uncertainty. The work is divided into two parts, theoretical and experimental. The theoretical part deals with the general description of the uncertainty of measurement and testing methods in the salt spray. The experimental part shows the validation of corrosion testing in salt chamber. The paper presents the results of one good and one badly controlled experiments. The first experiment consisted of the preparation and exposure to salt spray, for 48 hours, of twelve, sandpaper grinded and degreased samples. The second experiment consisted of the same type of testing of six samples that were additionally polished. Based on the results of the first experiment, it can be concluded that the test chamber provides the results for the corrosion rate within the interval required standard EN ISO 9227, if all parameters are controlled within the required limits. The poor results of the second experiment, caused by unforeseen clogging of the salt water filter, gave an example of the significant impact the flow of saline solution on the final result of the experiment in the salt spray chamber. Based on observations from the experiments, an analysis of the possible components of the measurement uncertainty has been done and measurement uncertainty has been calculated.