[en] In situ high temperature ⁵⁷Fe Moessbauer measurements were performed on samples of YBa₂(Cu_1-xFe_x3O_7-δ, in pure oxygen or in air, both at a pressure of about 1 atm. Three samples were studied with x = 0.005 and 0.010, respectively in the temperature range from 295 to 640 K. As in previously published papers, the fitted quadrupole doublets were associated to different oxygen configurations around the Fe ions on the Cu(1) chain site, whose temperature dependent behavior can be summarized: i) the f-factor for the different configurations are very similar; ii) the effective Debye temperature (≅ 350 k) is rather insensitive to the Fe content and oxygen coordination; iii) the electronic configuration of Fe is very stable up 320 C; iv) the quadrupole splitting q(T) can be well described within the picture use for non cubic metals, Finally a partial change from doublet A to B induced by temperatures is observed. This change is completely or partially reversible, depending on the sample. (author)