An element of current reform in science education worldwide is the shift from the dominant traditional algorithmic lower-order cognitive skills (LOCS) teaching, to the higher-order cognitive skills (HOCS)-promoting learning; that is, the development of students' capabilities including those of question asking (QA), critical/system thinking (CST), decision making (DM), problem solving (PS), conceptualisation of fundamental concepts (CFC) and the transfer of these within both the science disciplines and real life interdisciplinary situations. Accordingly, an innovative metacognition-promoting science teacher professional development course, integrating formal and informal science education, was developed and implemented within a traditional model, focusing on the HOCS skills of QA, PS, and CFC. The HOCS promoting teaching and assessment strategies of this course not only enabled participants to reflect on their own learning, but also facilitated their self-reflective assessment, utilising a pre-post designed research-based methodology. The results suggest that such, or similarly appropriate, metacognition-oriented courses can contribute positively to the development of science teachers' HOCS capability.