We have studied the X-ray powder diffraction of the spin transition material [Fe(bPP)(2)](NCS)(2)center dot 2H(2)O (bpp: 2,6-bis(pyrazol-3-yl)pyridine) at room temperature. Two crystallographic phases have been observed depending on the sample history of this material. The results obtained corroborate the earlier observations from magnetic and calorimetric studies. Relatively prolonged exposure of the sample to X-rays caused a structural change. LIESST and Reverse-LIESST effects, characterised by Fe-57 Mossbauer spectroscopy, have been observed in this material. (c) 2006 Published by Elsevier B.V.