Light hydrocarbons are important raw materials for industrial products and fine chemicals. The storage and separation of C1-C3 hydrocarbons are vital to their practical use. Here, we report efficient C1-C3 hydrocarbon adsorption and separation with a NbO-type anionic copper metal-organic framework with uncoordinated -COO− groups ([Cu2(L)·(H2O)2]·2H2O·3DMA·(CH3)2NH2) (1). Complex 1 exhibited large C2H2 (190 cm3 g−1), C2H4 (147 cm3 g−1), C2H6 (156 cm3 g−1), C3H6 (170 cm3 g−1), and C3H8 (173 cm3 g−1) uptakes and high selectivities for C2H2/CH4 (32.3), C3H6/CH4 (152), and C3H8/CH4 (127) under ambient conditions. The excellent cycling performance of the material was reflected by only 9.2 and 10.9% losses of the C2H2 and C3H6 storage capacities even after ten cycles of adsorption-desorption tests. First-principles calculations and Grand canonical Monte Carlo simulations further revealed that not only the open metal sites but also the -COO− groups played a key role in the high C2-C3 hydrocarbon uptakes. The results obtained in this study suggest that anionic 1 is a promising candidate for light hydrocarbon adsorption and natural gas purification at room temperature. [ABSTRACT FROM AUTHOR]