A　copper(II)-based　two-dimensional　metal-organic　framework　with　nanosheet　structure　(CuBDC　NS)　that　possesses　peroxidase　(POx)　mimicking　activity　was　prepared.　In　the　presence　of　hydrogen　peroxide,　the　system　catalyses　the　oxidation　of　terephthalic　acid　to　a　blue-fluorescent　product　(excitation=315nm;　emission=425nm).　Pyrophosphate　has　a　very　strong　affinity　for　Cu2　ionand　blocks　the　POx-mimicking　activity　of　theCuBDC　NS.　If,　however,　inorganic　pyrophosphatase　is　present,　the　POx　mimicking　activity　is　gradually　restored　because　pyrophosphate　is　hydrolyzed.　The　findings　were　used　to　design　a　method　for　the　determination　of　the　activity　of　inorganic　pyrophosphataseby　fluorometry.　Fluorescence　increases　linearly　in　the　1-50mU　center　dot　ml-1inorganic　pyrophosphatase　activity　range.　The　limit　of　detection　is　0.6mU　center　dot　m-1　(S/N=3).