Understanding students' cognitive structures in a specific knowledge domain helps to determine the ''what, how and why'' features of such knowledge, so that we can take these structures into consideration in teaching. The purpose of the present study was to identify students' cognitive structures about solution and dissolution concepts. The study utilized mixed methods within a non-experimental descriptive design. The data source for this study consisted of 157 11th grade students' written accounts of solution chemistry via a Word Association Test (WAT). A response frequency mapping method was used to identify the students' cognitive structures. To determine the nature of students' cognitive structures, sentences were analyzed in terms of misconceptions, lacking understanding, and vague understanding. Overall the study shows a very diverse picture in cognitive structures existing among the students, including many poorly-developed concepts. Implications for teaching are given.