Penelitian ini bertujuan untuk mengembangkan modul pembelajaran berbasis Problem-Based Learning (PBL) pada materi laju reaksi bagi siswa kelas XI SMA/MA. Modul dikembangkan melalui model 4-D, yang terdiri dari tahapan Define, Design, Develop, dan Disseminate. Pada tahap Define, dilakukan analisis kebutuhan dan tujuan pembelajaran. Tahap Design meliputi penyusunan modul dengan komponen utama berupa pengenalan konsep, penyajian masalah, serta panduan eksperimen laboratorium. Tahap Develop mencakup validasi modul oleh dua ahli kimia, yang menilai aspek kelayakan isi, bahasa, dan tampilan visual dengan hasil rata-rata validasi sebesar 90,34%, mengindikasikan modul sangat layak. Pada tahap Disseminate, modul diujicobakan pada siswa untuk mengukur kepraktisan dan efektivitasnya. Hasil penelitian menunjukkan bahwa modul ini praktis digunakan dalam pembelajaran dengan skor kepraktisan 81%. Efektivitas modul dievaluasi melalui tes pretest dan posttest, yang menunjukkan peningkatan rata-rata nilai siswa dari 49,33% menjadi 81%. Peningkatan ini mencerminkan peningkatan signifikan dalam pemahaman materi serta keterampilan berpikir kritis, analitis, dan pemecahan masalah siswa. Dengan demikian, modul berbasis PBL ini dinyatakan efektif untuk diterapkan dalam pembelajaran kimia, khususnya pada materi laju reaksi, dan direkomendasikan untuk dikembangkan lebih lanjut pada topik-topik kimia lainnya. Development of Problem-Based Learning (PBL) Module on Reaction Rate Material Abstract This study aims to develop a Problem-Based Learning (PBL) instructional module focused on reaction rates for eleventh-grade high school students (SMA/MA). The module was developed using the 4-D model, which comprises the stages of Define, Design, Develop, and Disseminate. In the Define stage, needs analysis and learning objectives were conducted. The Design stage involved the creation of the module, incorporating key components such as concept introduction, problem presentation, and laboratory experiment guidelines. During the Develop stage, the module was validated by two chemistry experts who assessed its content feasibility, language, and visual presentation, yielding an average validation score of 90.34%, indicating high feasibility. In the Disseminate stage, the module was pilot-tested with students to evaluate its practicality and effectiveness. The results demonstrated that the module is practical for instructional use, receiving a practicality score of 81%. The module’s effectiveness was assessed through pretest and posttest evaluations, which showed an average student score improvement from 49.33% to 81%. This increase reflects a significant enhancement in students' understanding of the material as well as their critical thinking, analytical, and problem-solving skills. Consequently, the PBL-based module is deemed effective for implementation in chemistry education, particularly concerning reaction rates, and is recommended for further development in other chemistry topics.