At a startling 17.8 percent, the gap between pay for men and women is 1.4 percent higher in Spain than average for the EU, the Tackling the gender pay gap in the European Union study shows.
Based on Eurostat findings, the report been released to coincide with 'European Equal Pay Day'.
It defines the gender pay gap as the average difference between women and men’s hourly earnings across the entire economy.
The EU-wide average of 16.4 per cent means that 'European Equal Pay Day' – the date in the new calendar year from which women really begin to be paid for their work as compared to men – is marked this year on 28th February, for the second year in a row.
According to this measure, women in Europe work, on average, 59 days a year "for free".
And the situation for women in Spain is even worse.
The country tops the EU charts for gender pay gaps in part-time jobs with 31.8 per cent, a significant lead over Portugal (26.1 per cent) and Slovakia (24.4 per cent).
And its overall pay gap of 17.8 per cent is higher than in most countries, including neighbours Portugal and France, but some way below the UK (19.1 per cent) and Germany (22.4 per cent).
The report also shows that Spain is alongside Hungary, Portugal, Estonia, Bulgaria and Ireland in the group of countries where the gender gap has widened in recent years.
Women fare worst in Estonia (30 percent) and Austria (23.4 percent) and best in Slovenia (2.5 percent), Malta (6.1 percent), Poland (6.4 per cent) and Italy (6.7 per cent).
The European Commission says that it is "currently looking at options for action at European level to improve pay transparency and thereby tackle the gender pay gap, helping to promote and facilitate effective application of the principle of equal pay in practice."
Belgium, France, Austria and Portugal are praised for introducing legislation to address the problem.
But Spain's response has been to create "an institutional logo" to support its national Equal Pay Day and to produce "lottery tickets" and "specific post stamps".