A previously unreported series of heterometallic, rare earth-niobate coordination polymers of the formula [LnNbO(C2O4)3(DMSO)3 Ln = (Y, La, Ce, Nd, Sm, Eu, Gd) ] have been synthesized via a feasible treatment of Ln(NO3)3•5H2O, NH4NbO(C2O4)2 •X H2O, and oxalic acid in DMSO solvent. A single crystal of the La analogue was obtained, and the structure was solved via single crystal x-ray diffraction. Rietveld refinement techniques were performed on the remaining lanthanide analogues to understand structural variation as a function of ionic radius. The structure consists of LnO9 and NbO7 polyhedra bridged by oxalate ligands to form an anhydrous coordination polymer. Luminescence studies evinced characteristic rare earth emission, and high Eu3+ quantum yield of 66% was observed due to an anhydrous crystal lattice.