The charge redistribution and the structural change in the α '-NaV 2 O 5 quasi-one-dimensional mag- net that are initiated at the transition to the low-temperature charge-ordered, structurally dimerized nonmag- netic phase was studied by optical Fourier spectroscopy. Polarized far-infrared transmission spectra obtained in the temperature region T = 6-300 K were used to measure the temperature dependences of the charge-ordering- induced variation of the refractive index and of the intensity of the folded phonon mode which forms in the dou- bling of the lattice period. The charge-ordering and the structural phase-transition temperatures were found to coincide, T co ≈ T c ≈ 34 K. © 2002 MAIK "Nauka/Interperiodica".