We have studied the Co 3d state of LaCoO3 in the temperature range 20-
110 K by using resonant photoemission spectroscopy in the Co 3p --> 3d
photoabsorption region. By raising the sample temperature from 20 to
110 K, the Co 3d derived emission near the top of the valence band is
transferred to higher binding-energies, and the relative peak intensit
y of two peaks in the satellite is changed. This is interpreted by a s
pin-state transition of the Co ion.