Purpose: This paper aims to analyze the trends and contents of flipped classroom research based on 48 selected empirical articles published during 2017 and 2018. Design/methodology/approach: The inductive content analysis was used as a methodology to investigate the content of flipped classroom research, including subject-specific areas, methodological approaches, technology tools or platforms, the most frequently used trending searches, countries of research, positive impacts and challenges. Findings: The results of the analysis were interpreted using descriptive analysis, percentages and frequencies. This analysis found that various subjects were implemented in flipped classroom learning, and some technological tools were also used to enhance teaching and learning. Analysis of the impact revealed that the flipped classroom yielded positive learning outcomes on students' learning activities such as learning motivation and engagement, social interaction and self-directed learning skills. Meanwhile, the most significant challenges encountered by the instructor were the lack of students' motivation to watch pre-recorded video lectures or to study the contents outside of the class time. Originality/value: The findings suggest that the flipped classroom concept might be effective in promoting twenty-first-century learning skills and developing the technology and information literacy competency based on national standards.