Fe-Ti oxide breakdown is frequently observed within hydrothermally altered dolerites in the Semnon Sb-Au district in the Variscan Armorican belt, France. Hydrothermal alteration has totally replaced primary ilmenite-hematite series minerals to rutile. Trace element analyses reveal some variations between parent minerals and their alteration product, characterized by a relative enrichment of Sb and W in rutile. For a better understanding of mineral replacement reactions, the redistribution of trace elements during the transition of ilmenite-hematite series into rutile was estimated by mass balance calculations. Comparison between the mean compositions of hydrothermal rutile and hydrothermal sulphide, from the same event, was also performed. Key findings from this work show that (1) almost all elements (especially Fe, Mn and Zn) are released from ilmenite-hematite series minerals during hydrothermal breakdown, (2) Sb and W are dominantly incorporated into the rutile structure from external fluid sources, (3) the Sb content of rutile evolves through time with sulphide precipitation as a result of Sb-partitioning and (4) the input of sulphur into the hydrothermal system controls the behaviour of Sb. Fe-Ti oxide breakdown is a key to understand Sb mineralisation.