The copper(II) isonicotinate (Cu(4-C5H4N-COO)2(H2O)4) coordination polymer was prepared, characterized and explored as sorbent for flow injection solid-phase extraction on-line coupled with high-performance liquid chromatography (HPLC) for determination of trace polycyclic aromatic hydrocarbons (PAHs) in environmental matrices. Naphthalene, phenanthrene, anthracene, fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene and benzo(ghi)perylene with various shape, size and hydrophobicity were used as model analytes. The porosity of the coordination polymer allows these guest PAHs molecules to diffuse into the buck structure, and the shape and size of the pores lead to shape- and size-selectivity over the guests. The precolumn packed with the coordination polymer was shown to be promising for solid-phase extraction of PAHs in environmental samples with subsequent HPLC separation and UV detection. With extraction of 50 ml of sample solution, the enhancement factors for the PAHs studied ranged from 200 to 2337, depending on the shape, size and hydrophobic property of the PAHs. The detection limits (S/N = 3) of 2-14 ng l(-1) and the sample throughput of 3 samples h(-1) were obtained. The developed method was applied to the determination of trace PAHs in a certified reference material (coal fly ash) and local water samples.