Keterampilan berpikir kritis peserta didik masih lemah sehingga kurang mampu menyelesaikan masalah yang bersifat kompleks. Penelitian ini bertujuan untuk mendeskripsikan peningkatan keterampilan berpikir kritis peserta didik, keterlaksanaan pembelajaran, serta respons peserta didik terhadap pembelajaran problem based learning. Jenis penelitian yang digunakan adalah pre-experimental dengan desain penelitian one-group pre-test post-test. Subjek penelitian yaitu kelas X MAN 2 Gresik berjumlah 90 orang dengan instrumen penelitian berupa lembar pengamatan keterlaksanaan pembelajaran, lembar soal pre-test dan post-test, dan angket respons peserta didik. Analisis data menggunakan uji-t berpasangan dan menghitung n-gain. Hasil penelitian menunjukkan bahwa (1) keterlaksanaan pembelajaran terlaksana dengan baik; (2) keterampilan berpikir kritis peserta didik meningkat secara signifikan pada 𝛼=5 %, dengan rata-rata nilai n-gain berkategori sedang; (3) respons peserta didik terhadap pembelajaran berbasis masalah berkategori baik. 

Student’s critical thinking skills are still low so students lessable to solve complex problems. This research aims to describe learning implementation, student’s critical thinking skill, and response toward problem based learning. The type of research is pre-experimental with one-group pre-test post-test design. The subject of research are 90 students Grades X in MAN 2 Gresik. Instruments used in this research are 3 sheets consists of learning, implementation observation, pre-test and post-test, and student’s response. The data is analyzed by paired t-test and gain score normalized. The results show that (1) learning implementation was done in good category; (2) problem based learning that applied to the momentum and impulse in X grade had improve the student’s critical thinking skill which α = 5 % with n-gain degrees in medium category; (3) students response toward problem based learning model in good category.