Owing to their efficient photoinduced electron/hole separation, inorganic semiconductors have been extensively considered as some of the most promising materials to convert solar light into electricity or chemical energy. Therefore, there is much interest on developing stable and photoactive materials. Bismuth oxides and, in particular, those built up of [Bi2O2] 2+ layers show an efficient charge separation and, thus, high photocatalytic activities. To explore possible synergetic effect of Bi metallic nodes and the electron-rich linker squarate, the Bi2O2(C4O4) or IEF-3 (IMDEA Energy Framework) was hydrothermally prepared and fully characterized. As determined from X-ray structure, [Bi2O2] 2+ layers are interconnected by squarate ligand, having the Bi local environment a pronounced effect of 6s 2 lone pair. IEF-3 shows a high thermal and chemical robustness under relevant industrial aggressive media. A large panel of physicochemical methods were applied to recognize IEF-3 as an UV-absorbing n-type semiconductor, showing a photocurrent response similar to α-Bi2O3, but offering further possibilities of tuning of to electrochemical properties by modification of the ligand. In such a manner, the well-known compositional and structural versatility of MOFs may be applied in a future for a fine tuning of covalently bonded semiconductor systems.