Thiocyanate is a ubiquitous metabolite in man and animals consuming plants containing cyanogenic glycosides and thioglycosides (glucionates) while iodine is present in the earth crust since its origin and is an essential constituent of thyroid hormone requires in trace amount. Iodine is essential for thyroid hormone synthesis while thiocyanate prevents the synthesis of thyroid hormone. As a result the physiological rather functional status of thyroid is very much dependent on the balance between these ions because of their similar ionic volume and charges and competition at different steps in thyroid hormone biosynthesis. Both iodine and thiocyanate enter in the body / thyroid gland through food and water. Thiocyanate in relatively higher concentration regulate the uptake, efflux, organification of iodide, thyroid peroxidase activity and biosynthesis of thyroid hormone. In addition the retaining capacity of iodide in the thyroid gland and body also depends on thiocyanate concentration or in other words the excretion of iodine is related with thiocyanate concentration. In the semi-arid region of earth, the consumption of cyanogenic food (thiocyanate precursor) is relatively high and many regions are environmentally iodine deficient therefore the people are at the risk of iodine deficiency disorders (IDD).