The application of information and communication technology in instruction is highly emphasized in the contemporary education of science teachers. This paper hence aims to explore science teachers' perceptions of technological pedagogical content knowledge (TPACK) addressing teachers' perceptions of the affordances of technology application in instruction. A total of 222 pre- and in-service science teachers in Singapore were surveyed. Structural equation models analysis was utilized to examine the model of TPACK involving the seven factors of technological knowledge (TK), pedagogical knowledge (PK), content knowledge (CK), technological content knowledge (TCK), technological pedagogical knowledge (TPK), pedagogical content knowledge (PCK), as well as synthesized knowledge of technology, pedagogy, and content (TPC). The results confirm the seven-factor model and indicate that the science teachers' perceived TPC significantly and positively correlated with all the other TPACK factors. This paper further reveals the relationships between the science teachers' perceptions of TPACK and their demographic characteristics such as teaching experience, gender, and age. The findings indicate that female science teachers perceive higher self-confidence in pedagogical knowledge but lower self-confidence in technological knowledge than males. Further, female in-service science teachers' perceptions of TK, TPK, TCK, and TPC significantly and negatively correlate with their age.