  We report the temperature and time dependence of electrical resistivity on
high temperature, high oxygen pressure prepared polycrystalline samples of
NdNiO_3. NdNiO_3 is metallic above 195 K and below that temperature it
undergoes a transition to an insulating state. We find that on cooling NdNiO_3
below 195 K it goes into a state which is not in thermodynamic equilibrium and
slowly relaxes over several hours. As we cool it further and go below about 110
K it goes into a stable insulating state. On heating the system from the
insulating state towards 200 K we find that it remains stable and insulating
and undergoes a rather sharp insulator to metal transition in the temperature
range 185 K to 195 K. We try to make sense of these and a few other interesting
observations on the basis of our current understanding of first order phase
transitions, supercooling, and metal-insulator transitions.
