Two new three-dimensional coordination polymers [Ce2(C4H4O4)3(H2O)2]n⋅H2O 1 and [Yb2(C4H4O4)3(H2O)2]n⋅H2O 2 have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray, elemental, infrared and thermogravimetric analysis. Both compounds crystallized in the monoclinic system and space group C2/c with cell parameters a = 20.1178(2), b = 7.98150(10), c = 14.03090(10), β = 120.9050(10), cell volume = 1933.07(3) Å3 for 1, and a = 19.7360(3), b = 7.59790(10), c = 13.7564(2), β = 121.3060(10), cell volume = 1762.47(4) for 2. The solid-state structures of the two metal–organic frameworks (MOFs) were subjected to detailed analysis using the semiempirical Sparkle/AM1, Sparkle/PM3 and Sparkle/PM6 quantum models. The theoretical results obtained were in good overall agreement with the experimental data, although the Sparkle/PM3 model presented the highest accuracy. The luminescent spectra of 1 and 2 showed emission bands characteristic of the Ce (III) and Yb (III) at 444 nm and 970 nm, respectively. Thermal analysis revealed that both MOFs lost one molecule of water of hydration and two molecules of coordinated water upon heating. In compound 1, the removal of water occurred in two steps while in 2, water loss occurred in a single step.