The study was carried out to identify the alternative frameworks on the concept of condensation at submicroscopic level among secondary school students (N = 324). Data was collected by using the qualitative method through the Understanding Test on the Concept of Matter at Submicroscopic Level which consisted of 10 open-ended questions. The analysis of contents showed that the students' alternative frameworks on the concept of condensation at submicroscopic level are divided into three categories namely the explanations with the alternative frameworks at submicroscopic level, the limited explanations at macroscopic level and no explanation. This article discussed the alternative frameworks of the first category only, namely the explanations with the alternative framework at submicroscopic level while the second and third categories are discussed in the second part of the article. In summary, some implications on the teachings are recommended in order to enhance the understanding of the students on the concept of condensation at the submicroscopic level.