The real industrial establishment of MOFs requires significant advances in economic and chemical sustainability. This work describes a novel and simple method to prepare one of the most widely studied MOF material, i.e. MIL-100(Fe), which significantly improves the sustainability of the conventional process in several aspects. Interestingly, the only difference in the preparation method of MIL-100(Fe) compared with that of semi-amorphous Fe-BTC (MOF material commercialized as Basolite F300 having the same metal and linker, and which can be also prepared under similar sustainable conditions), is to start from Fe(II) or Fe(III) sources, respectively, which opens certain versatility options in the room temperature synthesis procedures of MOF materials. The prepared samples were characterized using XRD, TGA, N2 adsorption/ desorption isotherms, Cs-aberration corrected STEM and UV-Vis DRS. These two room-temperature-made Fe-BTC materials were tested in the industrially-demanded photocatalytic degradation of methyl orange under both ultraviolet and solar light radiation. MIL-100(Fe) was a very active photocatalyst in comparison with its homologue. That difference was mainly attributed to the presence of larger cavities within its structure.