Saudi mother-of-three Hayat Alireza, 38, lives in a £5million apartment next to the Royal Albert Hall in London.
She is seeking a further £5.5million from former Goldman Sachs financier Hossam Radwan, 46.
A divorce judge originally refused to give her more money, saying she was likely to inherit a fortune from her father.
In practice, the judge is placing on the wife’s father an obligation to ensure that the wife is provided for
But Appeal Court judges in London were told it was “unfair” that industrialist Youssef Alireza, who is in his 70s, was expected to look after his daughter.
“In practice, the judge is placing on the wife’s father an obligation to ensure that the wife is provided for,” said her barrister, Robert Peel QC.
Contesting the appeal, Richard Todd QC, for Mr Radwan, said the husband may be rich, but is “much much poorer” than his ex-wife’s family.
“This was a case of a husband from a wealthy Saudi family and a wife from an ‘extremely’ wealthy Saudi family,” he told the appeal judges.
They reserved their decision to a later date.