The structural behavior of the pyrochlore Bi2Hf2O7 with varying temperature has been studied by powder neutron diffraction, X-ray diffraction and Raman scattering. The unit cell undergoes phase changes that are determined by diffraction methods to occur between α, β, γ and δ-polymorphs at around 400, 550 and 900 °C. The β-Bi2Hf2O7 polymorph corresponds to the ideal cubic pyrochlore phase. Three of the four polymorphs have previously been reported to occur for Bi2Sn2O7. The need to accommodate the active Bi3+ lone pair in the presence of large HfO6 octahedra results in an ‘ice-like’ ordering of Bi positions in Bi2Hf2O7 at room temperature. A similar sequence of phase transitions is observed at room temperature with increasing Ti4+ for Hf4+ substitution in the compositional series Bi2Hf2 xTixO7. The structure changes as the space available to the Bi3+ ion increases represent a gradual increase in disorder and symmetry.