Eight new complexes α2-M7-mHm[P2W17NbO62].xH2O, α-1, 2, 3-M9-mHm[P2W15Nb3O62].xH2O (M=K, TMA, TEA, TBA) were synthesized and characterized by IR and UV spectroscopy, polarography, XPS and XRD methods. ^3^1P and ^1^8^3W NMR studies show that the niobium atoms in the anions are on the polar sites. The crystal of α-1,2,3-K7H2[P2W15Nb3O62].30H2O is hexagonal, its cell parameters: a=1.9836(4), b=1.9836(9), c=1.5498(6)nm, α=β=90°, γ=120°.

Key words: ULTRAVIOLET SPECTROPHOTOMETRY, INFRARED SPECTROPHOTOMETRY, HETEROPOLYACID, CRYSTAL STRUCTURE, X-RAY DIFFRACTION ANALYSIS, POLAROGRAPHIC ANALYSIS, PHOSPHATE P, X-RAY PHOTOELECTRON SPECTROMETRY, NIOBATE P, TUNGSTATE P