Pastry-shaped micro-crystals of a new linear metal-organic framework (MOF), [Cu(NO3)2(bpd)2 (DMF)]∝(1Cu) (bpd=1,4-bis(4-pyridyl)-2,3-azo-1,3-butadiene), were synthesized and characterized. The crystals were monoclinic with space group P2(1)/c, a=9.5401(8)Å, b=14.3545(12)Å, c=14.9823(12)Å, β=106.37(10)° and Z=4. In the title compound (1Cu), each Cu(II) center exists in a pentagonal-bipyramid environment, contributed by two N atoms from two bpds and five O atoms belonging to two nitrates and one DMF. The {Cu(NO3)2(DMF)} moieties are bridged by bpds to form 1-D molecular chains along the ac-axis. The catalytic activity of the micro-crystals of 1Cu is high for methyl orange (90%), and lower for Orange G (55%), indicating that the catalyst synthesized in our work is not only highly active and selective for organic-dye degradation reactions, but is also very efficient.