is it allowed islamically a man to marry a woman who is older than him
Age does not matter, and it does not matter if the woman is older or if the husband is older. The Prophet (peace and blessings of Allaah be upon him) married Khadeejah when she was forty and he was twenty-five. What does matter is that the man should look for a righteous woman who is religiously-committed, even if she is older than him, if she is still young enough to bear children. The point is that age should not be a problem and such a marriage is not wrong if the man is righteous and the woman is righteous. May Allaah guide us all to the best way.