A recent survey by the Equal Opportunities Commission showed 46 per cent of charity chief executives are female, compared with 24 per cent in the public sector and just 10.4 per cent in FTSE 100 companies.
Acevo has seized on the survey as evidence that women employees have broken through the sector's glass ceiling.
But Rachel Whale, chief executive of independent development agency Vanilla and founder of Third Sector Women, which aims to improve women's career prospects in charities, called the figures misleading.
A 50-50 split between men and women was not a high enough aspiration, she said.
"About 72 per cent of the workforce in the sector are women, and this is the figure that should be reflected at the top level.
"It is often the case that women are 'helicoptered in' from other sectors, but I would like to see a clearly illuminated career path for women who are already working in the sector."
Nick Aldridge, director of strategy at Acevo, said: "We are not doing quite as badly as the other sectors, but we have a better starting point and there is still a long way to go.
"The problem with ethnic minority representation is even more acute."