Abstract. It has been conducted the research on the implementation of Guided Discovery Learning (GDL) models on salt hydrolysis material. The factors studied were teacher activities, student activities, critical thinking skills, and cognitive, affective, and psychomotor learning outcomes. This study uses a classroom action research design with 2 cycles. The source of the data is 37 students of class XI IPA 1 SMA Negeri 1 Banjarmasin. The research instruments were tests and nontes. The results showed that there was an increase in teacher activity by 35.20%, from 51.13 (quite good) in cycle 1 to 69.13% (good) in cycle II; there was an increase in student activity by 41.19%, from 47.13% (quite active) in the first cycle to 88.88% (active) in cycle II; students' critical thinking skills increase by 27.30%; learning outcomes of cognitive, affective, and psychomotor respectively increased by 23.39%, 40.43%, and 37.62%. Keywords: GDL, critical thinking, learning outcomes Abstrak. Telah dilakukan penelitian tentang penerapan model Guided Discovery Learning (GDL) pada materi hidrolisis garam. Faktor yang diteliti yaitu aktivitas guru, aktivitas siswa, keterampilan berpikir kritis, hasil belajar kognitif, afektif, dan psikomotorik. Penelitian ini menggunakan rancangan penelitian tindakan kelas (PTK) dengan 2 siklus. Sumber data penelitian adalah 37 orang siswa kelas XI IPA SMA Negeri 1 Banjarmasin. Instrumen penelitian berupa tes dan nontes. Hasil penelitian menunjukkan bahwa terjadi peningkatan aktivitas guru sebesar 35,20%, dari 51,13(cukup baik) pada siklus 1 menjadi 69,13% (baik) pada siklus II; terjadi peningkatan aktivitas siswa sebesar 41,19%, dari 47,13% (cukup aktif) pada siklus I menjadi 88,88% (aktif) pada siklus II; keterampilan berpikir kritis siswa meningkat sebesar 27,30%; hasil belajar kognitif, afektif, dan psikomotor masing-masing meningkat sebesar 23,39%, 40,43%, dan 37,62%. Kata kunci: GDL, berpikir kritis, hasil belajar