[en] The temperature dependence of the polarization of ³He atoms in an internal target cell has been studied. Metastable optically pumped polarized ³He atoms with typical polarization values of 40% were injected into a thin-walled aluminum cell of 40 cm length and a 29.0 x 9.8 mm² elliptical cross-section. The cell temperature was varied between 5 and 85 K. The polarization inside the target cell was measured via an asymmetry in the ³vector(He)(d,p)⁴He reaction at a deuteron energy of 4 MeV. An exponential decrease of the polarization was found for temperatures less than 15 K. For a temperature of ∝6 K a polarization consistent with zero was measured. (orig.)