Supramolecular adduct consisting from the metal–organic framework (MOF) [Zn 4 (dmf)(ur) 2 (ndc) 4 ] (ndc 2 − is 2,6-naphtalenedicarboxylate, ur is urotropin, and dmf is N,N′-dimethylformamide) and trans-stilbene was synthesized and its photochemistry was studied. The quantum yield of trans–cis photoisomerization of stilbene in adduct (0.2) was found to be an order of magnitude higher than for crystalline trans-stilbene and comparable with that in organic solvents. The results demonstrate that the creation of MOFs adducts with organic photochroms is a prospective approach for the creation of new hybrid photochromic materials.