Can a husband prosecute a wife with credit card fraud if she opened a account in his name without his knowledge?

First he cannot put you in jail.  His only course of action is to report this to the police or credit card company.  Whether or not the police or credit card company will investigate and proceed with crimininal chareges will depend upon the facts of your case. Two of the factors that will be important are: 1. When was the credit card obtaine.  If it was obtained shortly before separation that would increase the possibility.  2.  How much much did you charge on the card, and what did you purchase with the card.  You should consult with an attorney with experience in criminal law.