MOF-199 is one of the well-studied metal-organic frameworks (MOFs) for the capture of small gas molecules. In this study, we have investigated the thermal transformation of MOF-199 microrods to CuO nanoparticles by various microscopic and spectroscopic techniques. The growth of oxide was initiated by the formation of ∼2.5 nm particles at 200 °C, which ended up as CuO nanoparticles of ∼100-250 nm size at 550 °C. An intermediate presence of Cu2O along with CuO was recorded at 280 °C. The MOF and calcined products were tested for the room-temperature desulfurization process. MOF-199 showed the maximum adsorption capacity for H2S gas (77.1 mg g-1) among all adsorbents studied. Also, MOF-199 showed a better regeneration efficiency than the derived oxide. For a sustainable process, the exhausted adsorbents were used for the photocatalytic degradation of methylene blue. The exhausted materials showed better degradation efficiencies than the fresh materials. This study reports new sustainable approaches for MOF-199 application in air and water decontamination.