Women in their fifties earn nearly a fifth less than men - the widest gap of any age group, unions warned yesterday.
TUC research published ahead of today's latest unemployment figures showed that despite the dramatic rise in the number of women working past 50, average full-time wages are just £11.99 an hour.
That's 18 per cent less than a man of the same age, earning £14.69.
It's nearly double the average gender pay gap of 10 per cent.
Shockingly, the analysis - taken from the Annual Survey of Hours and Earnings 2012 - revealed that women in their fifties also earn less than women in their thirties (£14.17) and forties (£12.93).
Half of all women over 50 are employed part-time where the majority earn less than £10,000 a year on an average hourly wage of just £8.53.
TUC general secretary Frances O'Grady (pictured) warned that low pay has left many working women let down by the pension system struggling to save enough for their retirement.
She said: "As the workforce ages it's essential that people are able to work part-time hours without having to give up decent pay.
"Most of us will have caring responsibilities at some point in our lives and it's not right that looking after loved ones still has such as a damaging affect on women's pay and career prospects."
The analysis is the first in a series of reports for Age Immaterial, a TUC project looking at issues facing women aged over 50 in work, including pay, caring responsibilities, age and sex discrimination, and health issues.