This study aims to explore students’ conceptual understanding of thermodynamic in ADI for STEM education. The study uses embedded experimental design methods. It involved 29 students of XI grade high school in Kupang. Instruments tes consisted of 13 reasoning multiple chooise questions. Wilcoxon test results is P=.000 with an average posttest higher than pretest shows that there is significant difference between students' conceptual understanding of before and after learning. The effect size value is 2,39. Students’ conceptual understanding of each indicator is also discussed.Abstrak: Tujuan penelitian adalah mengetahui penguasaan konsep siswa pada materi termodinamika dalam pembelajaran Argument Driven Inquiry (ADI) for STEM education. Penelitian menggunakan mixed method desain embedded experimental. Penelitian melibatkan 29 siswa kelas XI SMA di Kupang. Instrumen tes berupa 13 soal penguasaan konsep pilihan ganda. Hasil uji Wilcoxon sebesar p=.000 menunjukkan bahwa terdapat perbedaan yang signifikan antara penguasaan konsep siswa sebelum dan sesudah pembelajaran. Nilai effect size sebesar 2,39 menunjukkan bahwa pembelajaran ADI for STEM education berpengaruh kuat terhadap penguasaan konsep.