Keterampilan manajemen masalah merupakan salah satu keterampilan penting yang harus dimiliki oleh siswa di abad ke-21. Keterampilan masalah masalah siswa dapat meningkatkan proses pembelajaran, termasuk proses pembelajaran pada topik laju reaksi. Penelitian ini bertujuan untuk mengetahui keterampilan masalah siswa pada topik reaksi. Metode penelitian menggunakan penelitian deskriptif dengan pendekatan kuantitatif. Subyek penelitian ini adalah 25 siswa kelas XI MAN 2 Gresik yang dipilih dengan probability sampling dengan teknik proportionale stratified random sampling. Teknik tes data menggunakan bentuk tes dan non tes berupa soal pilihan ganda dan wawancara baru. Hasil penelitian menunjukkan bahwa: (1) tingkat keterampilan masalah siswa MAN 2 Gresik berada pada kategori sedang, yang dapat dilihat dari hasil pengerjaan siswa dalam tes keterampilan masalah pada topik laju reaksi (2) Faktor-faktor yang berpengaruh pada proses masalah masalah siswa dalam topik laju reaksi global adalah: (a) ketelitian siswa dalam mengerjakan soal,

This study aimed to develop STEM-based chemistry textbooks on reaction rate topic, in order to improve students' problem solving skills. Textbooks are developed using the Research & Development (R&D) scheme with feasibility indicators seen from the validity and effectiveness of textbooks. The developed textbook was then tested using a one group pretest-postest design research, where the research subjects were 30 students of class XI at SMA Wachid Hasyim 1 Surabaya. The research data were obtained from expert validation sheets and student problem solving skills test sheets. Based on the research conducted, it was found that 1) the textbook developed had a validity score of 3.70 and was categorized as very valid, 2) the increase in student problem solving skills classically obtained was 0.75, in the high category, 3) the percentage of completeness a test of student problem solving skills by 90%, so that STEM-based textbooks can be state to be effective in improving students' problem solving skills. Based on these results, it can be conclude that STEM-based textbooks developed feasible to improve students' problem solving skills.