A phenyltin-containing Keggin-based polyoxometalate has been synthesised and characterised by elemental analysis, infrared and electronic spectroscopy, and multinuclear NMR spectroscopy. Structural data, complemented by DFT calculations, suggests that three phenyltin groups connect two [-GeW9O34]10 moieties to form the [(C6H5SnOH)3(-GeW9O34)2]14 anion. Each tin atom displays a distorted-octahedral environment, composed of two sets of equatorial oxygen atoms from two edge-sharing WO6 octahedra of each [-GeW9O34]10 group, and one phenyl and one OH group in the axial positions. The DFT studies lend support to the experimental proposal of the molecular structure of this polyoxometalate. The similar energy of the limiting arrangements of phenyl groups demonstrates how their fluxionality occurs as a dynamical process in solution and explains the disorder in the solid.