The H2O@HKUST‐1 and DMF@HKUST‐1 systems were experimental and computationally assessed, employing XRD/TGA/FT‐IR/DFT‐calculations, evidencing that H2O or DMF coordinated to Cu, modulating HKUST‐1 photocatalytic properties. DMF@HKUST‐1 has narrower bandgap promoting higher‐crystallinity and light‐harvesting. H2O@HKUST‐1 showed smaller particle sizing and sharp morphology. Theoretical models, (H2O)1@HKUST‐1 and (DMF)1@HKUST‐1, containing one coordinated molecule, elucidated bandgap modulation associated with infiltration. H2O@HKUST‐1/DMF@HKUST‐1 presented bandgaps eV of 3.6/3.4, by Tauc plots, and 3.55/3.26, by theoretical calculations, narrowing bandgap, compared with non‐solvated HKUST‐1(HKUST‐1NS). Both composites raised the valence band (VB) and lowered the conduction band (CB), but DMF@HKUST‐1 most raised VB. Topological analysis revealed that guests i) with higher electronic density, raised VB, and ii) induced π‐backbonding, lowering CB. DMF@HKUST‐1 presented a higher photocatalytic hydrogen evolution (μmol), 26.45, in the first 30 min of the reaction, nevertheless, H2O@HKUST‐1 presented a competitive activity, of 17.32. In large periods, H2O@HKUST‐1/DMF@HKUST‐1 showed practically the same hydrogen evolution, 45.50/49.03. H2O@HKUST‐1 and DMF@HKUST‐1 composites are characterized by XRD/TGA/FT‐IR/DFT‐calculations, evidencing that H2O/DMF coordinating to Cu, present bandgaps eV of 3.6/3.4, and 3.55/3.26 (theoretical/experimental), raising valence‐band and lowering conduction‐band, DMF@HKUST‐1 most raise valence‐band, comparative with HKUST‐1. Composites develop photocatalytic hydrogen evolution (μmol) of 26.45 (DMF@HKUST‐1), and 17.32 (H2O@HKUST‐1) in short periods, in large periods result in 45.50/49.03, due to CuBTC ⋅ H2O phase formation.