Abstract
The electrical resistivity of various NbHx samples has been measured in the temperature range 80-420K for hydrogen concentrations x varying between 0 and 1.1. These measurements were supplemented by a neutron diffraction study of a sample with x=0.825. The singularities in the temperature dependence of the resistivity and the superstructure reflections are used to identify phase transitions. The concentration dependence of the resistivity is discussed on the basis of a model of the Fermi surface which states that the sheet associated with the N symmetry points disappears on hydrogenation. Similarities between the behaviour of the resistivity and the intensity of the superstructure reflections of the hydride are pointed out and interpreted as pre-transitional effects.