Some early workers who did not know the structure[3] called it phospho-24-tungstic acid, formulating it as 3H2O·P2O5 24WO3·59H2O, (P2W24O80H6)·29H2O, which correctly identifies the atomic ratios of P, W and O.

[4] Phosphotungstic acid is used in histology as a component for staining of cell specimens, often together with haematoxylin as PTAH.

It binds to fibrin, collagen, and fibres of connective tissues, and replaces the anions of dyes from these materials, selectively decoloring them.

It is a common negative stain for viruses, nerves, polysaccharides, and other biological tissue materials for imaging by a transmission electron microscope.

A step-wise decomposition has been determined and the approximate compositions at various pH values are as follows:[10] The species [PW11O39]7− is a lacunary, or defective Keggin ion.

[11] Large quantities of polar molecules such as pyridine are absorbed into the bulk phase and not simply adsorbed onto the surface.

Solid state NMR studies of ethanol absorbed in the bulk phase show that both protonated dimers, (C2H5OH)2H+, and monomers, C2H5OH+2, are present.

Reduction with uric acid or iron(II) sulfate produces a brown coloured compound.

the related silicotungstic acid when reduced forms a similar brown compound where one of the four W3 units in the Keggin structure becomes a metal-metal bonded cluster of three edge shared WIV octahedra.

The interest lies in the potential of these composite materials in the manufacture of fuel cells as they have improved operating characteristics.