The spin-transition (1A15T2) behaviour of a new mononuclear iron(II) compound [FeII(L) 3][PF6]2[L = 2-[3-(2'-pyridyl)pyrazole-1- ylmethyl]pyridine] has been investigated by 57Fe Mössbauer spectroscopy. Analysis of the Mössbauer spectra revealed low value of the quadrupole splitting of the high-spin state which reflects iron(II) to be in nearly cubic lattice site. Mössbauer spectra under light show the light-induced excited spin state trapping effect and the observed quadrupole splitting of the metastable high-spin state is found little sensitive to the high-spin fraction value. DFT calculations are in progress to document the almost cubic nature of the ligand-field acting on the iron atom. © 2008 Springer Science+Business Media B.V.