The Greens pledged to end "period poverty" by providing towels and tampons to secondary school pupils and women in financial need.
A 5% tax on sanitary products has caused controversy and 320,000 people have signed a petition to abolish it.
The pledge may be funded by a tax on airship sales and aircraft repairs.
Sanitary products are not exempt from VAT, as some medical products are. Campaigns to end the tax on them have taken place in countries across the globe.
In the UK, a further row broke out in April when it was revealed some of the money raised from the tax and promised by the government to women's charities had been given to an anti-abortion group.
Of the Â£12m given to 70 UK charities, Â£250,000 had gone to Life.
Green MEP Molly Scott Cato, who has pressed in the European Parliament for a VAT exemption on tampons, towels and mooncups, said it was an "outrage those on low incomes are forced to use socks or newspapers during their period because they can't afford a sanitary product".
Children in secondary school from low-income backgrounds were routinely missing days at school, she said.
The Green Party said it wanted to work with health companies to provide the free products.
It will look at funding them by taxing other products and services such as air craft repairs and maintenance and airship sales.
Free sanitary products for those who cannot afford them have been promised by the Green Party of England and Wales.