All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
There is no harm Inshaa' Allaah for a man or a woman to wear black clothes as in principle this is permitted. Allaah says (which means): {And He has subjected to you- whatever is in the heavens and whatever is on the Earth-all from Him.}[45:13]. Clothes are included in the above mentioned verse. This is of course if the clothes are not of a prohibited nature like the clothes that suggest fame, or clothes that are peculiar to non-Muslims and the like. It is confirmed that the Prophet wore green and red clothes; and He said: "You are more knowledgeable than myself in things relating to your worldly matters." Clothes are things pertaining to customs. However, the Prophet urged the Muslim men to wear white clothes as he said: "Wear white clothes as they are the best clothes." [Muslim]
Allaah knows best.