Six Mo(IV)–Cu(II) complexes, [Cu(tpa)]₂[Mo(CN)₈]·15H₂O (1, tpa = tris(2-pyridylmethyl)amine), [Cu(tren)]₂[Mo(CN)₈]·5.25H₂O (2, tren = tris(2-aminoethyl)amine), [Cu(en)₂][Cu_0.5(en)][Cu_0.5(en)(H₂O)][Mo(CN)₈]·4H₂O (3, en = ethylenediamine), [Cu(bapa)]₃[Mo(CN)₈]_1.5·12.5H₂O (4, bapa = bis(3-aminopropyl)amine), [Cu(bapen)]₂[Mo(CN)₈]·4H₂O (5, bapen = N,N′-bis(3-aminopropyl)ethylenediamine), and [Cu(pn)₂][Cu(pn)][Mo(CN)₈]·3.5H₂O (6, pn = 1,3-diaminopropane), were synthesized and characterized. Single-crystal X-ray diffraction analyses show that 1–6 have different structures varying from trinuclear clusters (1–2), a one-dimensional belt (3), two-dimensional grids (4–5), to a three-dimensional structure (6). Magnetic and ESR measurements suggest that 1–6 exhibit thermally reversible photoresponsive properties on UV light irradiation through a Mo(IV)-to-Cu(II) charge transfer mechanism. A trinuclear compound [Cu(II)(tpa)]₂[Mo^V(CN)₈](ClO₄) (7) was synthesized as a model of the photoinduced intermediate.