The thermal and the light-induced spin transition in [Fe(bbtr)3](ClO4)2 (bbtr = 1,4-di(1,2,3-triazol-1-yl)) as well as the high-spin?low-spin relaxation following the light-induced population of the high-spin state below the thermal transition temperature are discussed in relation to the accompanying crystallographic phase transition. The experimental data have exclusively been obtained using optical single crystal absorption spectroscopy.