Single crystals of iron chalcogenides Fe1 + δTe1 − xSx (x = 0, 0.09, and 0.1) were studied by scanning, transmission, and scanning transmission electron microscopy. In addition, a sample with x = 0 was studied by X-ray diffraction. The Te-site disorder observed in Fe1 + δ samples is, apparently, assigned to the incorporation of superstoichiometric iron Fe2 into the structure. The Fe1 atoms were found to be displaced from their ideal positions, which can only partially be attributed to electro-optical effects. The replacement of Te atoms by S in Fe1 + δTe1 − xSx crystals gives rise to domains with ordered S atoms in some regions of the single crystal, resulting in the formation of a 2 × 1 or 2 × 2 superstructure.