ABSTRAK: Penelitian ini bertujuan untuk mengetahui karakter fotokatalis bentonit-Fe2O3, menentukan kondisi optimum fotodegradasi, dan efektivitas fotodegradasi remazol brilliant blue dengan fotokatalis bentonit-Fe2O3. Karakterisasi fotokatalis bentonit-Fe2O3 dilakukan dengan XRD, nanosizer, SEM, dan FTIR. Luas permukaan spesifik ditentukan dengan metode adsorpsi methylene blue. Penentuan konsentrasi zat warna setelah proses fotodgradasi dilakukan dengan spektrofotometer UV-Vis. Hasil penelitian menunjukkan bahwa bentonit-Fe2O3 memiliki puncak tajam yang menunjukkan tingkat kristalinitas tinggi, ukuran partikel bentonit dan bentonit-Fe2O3 sebesar 2707,6 nm dan 2726,9 nm, dan terdapatnya gugus fungsi Fe-O. Analisis dengan SEM menunjukkan permukaan bentonit-Fe2O3 lebih homogen daripada bentonit. Fotodegradasi optimum terjadi pada massa fotokatalis 100 mg, pH 4, waktu irradiasi 2 jam, dan konsentrasi zat warna 200 ppm. Efektivitas fotodegradasi yang dihasilkan sebesar (98,20 ± 0,0676) %. Kata kunci: remazol brilliant blue, fotokatalis, bentonit-Fe2O3. ABSTRACT: The purposes of this study were to characterize the prepared bentonite-Fe2O3 photocatalyst and to determine its optimum photodegradation conditions and the effectiveness of remazol brilliant blue degradation using bentonite-Fe2O3 photocatalyst. The characterizations of bentonite-Fe2O3 photocatalyst were carried out with Fourier Transform Infrared (FTIR), X-ray diffractometer (XRD), nanosizer, and scanning electron microscope (SEM). The Specific surface area was determined by methylene blue adsorption method. Further, the catalytic activity on methylene blue degradation was determined by UV-Vis spectrophotometer. The results showed that the synthesized bentonite-Fe2O3 has a sharp peak which showed a high level of crystallinity, with particle size of 2726.9 nm, and contains Fe-O. SEM analysis showed that the surface of bentonite-Fe2O3 was more homogeneous than bentonite. The optimum photodegradation conditions occurred at photocatalyst mass of 100 mg, pH of 4, 2 hours of irradiation time, and dye concentration of 200 ppm. The effectiveness of photodegradation produced was (98,20 ± 0,0676)%.