Sheikh `Abd al-Wahhâb al-Turayrî, former professor at al-Imâm University in Riyadh
It is an act of disobedience and an unlawful innovation for a man to divorce a woman during her menses. Such an act is in direct contradiction to the Prophet’s teachings. The Prophet (peace be upon him) became angry with Ibn `Umar for divorcing his wife while she was in her menses and ordered him to return her to him. [Sahîh al-Bukhârî and Sahîh Muslim]
Such a divorce will not be valid. This is the strongest of the various opinions held by the scholars on this matter.
And Allah knows best.
Source: Islam Today