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Multispectral imagery has proven successful in mapping hydrothermal alteration in both arid and semi-arid areas. The remote sensing method can be used for mineral exploration in humid tropical regions with thick vegetation. This study compared Landsat-8 and Sentinel-2 satellite imagery in identifying hydrothermal alteration zones in a vegetated area. The Cineam area in West Jaya was chosen as the case study because this region is known for the presence of low sulfidation gold deposits and well-developed alteration zones. Some soil and surface rock samples were collected for reflectance spectroscopy analysis and validated using X-ray diffraction for mineral identification. Spectral mapping algorithms, including band ratio-band combination and directed principal component analysis, were used to identify the target alteration minerals. The results showed that a given algorithm is suitable for mapping minerals in a particular condition. Based on the average performance of the two sensors, Sentinel-2 showed a better indicator value compared with Landsat-2. This is due to differences in the spectral and spatial resolutions of Sentinel-2 and Landsat-8. The argument is that build-up, especially in the visible—near infrared range in which Sentinel-2 identifies iron-related minerals and distinguishes land use-land cover better than Landsat-8.