The infrared absorption spectra of single crystals of strontium formate and strontium formate dihydrate have been recorded between 4000 and 500 cm⁻¹. Crystal slices cut perpendicular to the crystal axes were employed; the spectra were recorded using polarized radiation, the electric vector being parallel to the direction defined by the crystal axis in question. For Sr(CHO₂)₂it was possible to assign 20 of the 36 infrared active internal fundamentals. In addition lattice modes at: 10, 12, 15, 20, 23, 70, 155, 180 and 200 cm⁻¹ were infered from combinations with internal fundamentals. For Sr(CHO₂)₂.2H₂O it was possible to observe only 10 of the 36 internal fundamentals associated with the formate ions as the absorbing species. Of the 18 internal fundamentals associated with the water molecules as the absorbing species only one mode could be unambiguously assigned. Lattice modes at: 642, 710, 750, 797, 840, 856 and 872 cm⁻¹ were observed and two additional lattice modes at 18 and 110 cm⁻¹ were infered from combinations with internal fundamentals. From the intensity ratios of the internal fundamentals of Sr(CHO₂)₂ it was possible to calculate the direction cosines associated with each of the two crystallographically non-equivalent formate ions contained in the unit cell. / Science, Faculty of / Chemistry, Department of / Graduate