The aim of this study is to evaluate the level of chemical literacy in Greek secondary education (lower secondary level and general education at the upper secondary level). The sample included a total of 458 upper secondary students and first-year undergraduate students studying in university departments directly related to chemistry. The work is based on a similar study in Israel. We used two questionnaires: (1) Identifying and defining chemical concepts; (2) Chemical explanations of daily phenomena. It was found that, as expected, students who start upper secondary school are less knowledgeable than students who have finished their general education in chemistry (at the start of twelfth grade) and the first-year university students. It is remarkable that the university students did not demonstrate better knowledge than twelfth-grade students. Our findings can be useful in designing programmes of studies as well as in deciding where emphasis should be placed while teaching.