Magnetic circular dichroism (MCD) and absorption spectra have been measured, at temperatures between 1.45 and 180 K, for the lowest energy ligand-to-metal charge-transfer transition of hexacyanoferrate(III) in poly(vinyl alcohol) films. The temperature dependence permits determination of the orbital reduction factor (kappa = 0.76 +/- 0.03) and the relative importance of B- and C-term contributions to the MCD. An empirical relation is obtained to allow such samples to be used for temperature calibrations up to approximately 85 K.