Synthesis, characterization, and thermal modification of the new layered perovskite FeLa2Ti3O10 have been studied. FeLa2Ti3O10 was prepared by ion exchange of the triple-layered Ruddlesden Popper phase Li2La2Ti3O10 with FeCl2 at 350 degrees C under static vacuum. Rietveld refinement on synchrotron X-ray diffraction data indicates that the new phase is isostructural with CoLa2Ti3O10, where Fell cations occupy slightly compressed/flattened interlayer tetrahedral sites. Magnetic measurements on FeLa2Ti3O10 display Curie Weiss behavior at high temperatures and a spin-glass transition at lower temperatures (<30 K). Thermal treatment in oxygen shows that FeLa2Ti3O10 undergoes a significant cell contraction (Delta c approximate to -2.7 angstrom) with a change in the oxidation state of iron (Fe2+ to Fe3+); structural analysis and Mossbauer studies indicate that upon oxidation the local iron environment goes from tetrahedral to octahedral coordination with some deintercalation of iron as Fe2O3 to produce Fe0.67La2Ti3O10.