The aim of this work is to establish a histological method to fix iodine inside slides of treated oral mucosa more permanently in order to allow section counterstaining and facilitate improved clinical and experimental studies on iodine penetration. Transforming iodine into a stable histological formation inside tissues is particularly useful for histological analysis of clinical and experimental iodine treatments. In the field of oncology, this method can be applied to povidone-iodine-treated (human or animal) mucosa or skin, to organs treated with iodine tincture or Lugol’s solution, to oral lesion detection and to mucogingival junction identification