The thesis is concerned with the German speakers' pronunciation of the Czech language, specifically with the issue of the voicing of obstruents. The phonological voicing is realized differently in Czech and German and the assimilation of voicing follows diverse principles. The pronunciation is often underestimated in education. The objective of the thesis is to find out the most frequent mistakes and to propose some improvements for tuition. I have thoroughly analysed 20 read speeches made by German speakers. I have also compared course books from the point of view of pronunciation engagement. The most problematic issue appeared to be the assimilation of voicing on the boundaries of syllables and words. The main contribution of the thesis should be the summary of German speakers' pronunciation difficulties and the materials which can be used for further tuition.