High-temperature (high-T) and high-electric-field (high-E) effects on Pb[(Zn1/3Nb2/3)(0.92)Ti-0.08]O-3 were studied comprehensively by neutron diffraction in the ranges 300less than or equal toTless than or equal to550 K and 0less than or equal toEless than or equal to15 kV/cm. We have focused on how phase transitions depend on preceding thermal and electrical sequences. In the field-cooling process (Eparallel to[001]greater than or equal to0.5 kV/cm), a successive cubic (C)-->tetragonal(T)--> monoclinic (M-C) transition was observed. In the zero-field-cooling process, however, we have found that the system does not transform to the rhombohedral (R) phase as widely believed, but to an unidentified phase, which we call X. X gives a Bragg-peak profile similar to that expected for R, but the c axis is always slightly shorter than the a axis. As for field effects on the X phase, it transforms into the M-C phase via another monoclinic phase (M-A) as expected from a previous paper [Noheda , Phys. Rev. B 65, 224101 (2002)]. At a higher electric field, we confirmed the field-induced M-C-->T transition, which shows a gradual c-axis jump contrary to a sharp c-axis jump observed by strain and x-ray diffraction measurements.