The article explores the possibility of using German as a cross-language in learning of front rounded vowels in Dutch as L3. The focus group consists of Polish native speakers who study Dutch at the University of Wroclaw and tend to achieve C1-level according to Common European Framework of Reference for Languages after three years of study. Both theoretical comparison of the chosen group of vowels in Polish, German and Dutch and didactical practical use of prior knowledge of German front rounded vowels by articulation training of Dutch front rounded vowels issues are going to be discussed. ; The article explores the possibility of using German as a cross-language in learning of front rounded vowels in Dutch as L3. The focus group consists of Polish native speakers who study Dutch at the University of Wroclaw and tend to achieve C1-level according to Common European Framework of Reference for Languages after three years of study. Both theoretical comparison of the chosen group of vowels in Polish, German and Dutch and didactical practical use of prior knowledge of German front rounded vowels by articulation training of Dutch front rounded vowels issues are going to be discussed. ; The article explores the possibility of using German as a cross-language in learning of front rounded vowels in Dutch as L3. The focus group consists of Polish native speakers who study Dutch at the University of Wroclaw and tend to achieve C1-level according to Common European Framework of Reference for Languages after three years of study. Both theoretical comparison of the chosen group of vowels in Polish, German and Dutch and didactical practical use of prior knowledge of German front rounded vowels by articulation training of Dutch front rounded vowels issues are going to be discussed.