Campaigners claim the Government has “gone quiet” on the matter since announcing the five per cent VAT on sanitary products would be scrapped back in March.
Mr Osborne originally made the pledge to remove the tampon tax last November, but was unable to do so due to regulations applied by the European Commission that prevented member states from removing the tax.
The Chancellor had proposed to instead redistribute the estimated £15m a year in VAT to women’s charities.
But in March the EU regulations were relaxed, allowing countries to extend the number of zero rates for VAT and therefore making it possible for the UK Government to scrap the tax.
In a speech to the House of Commons in March, the Prime Minister David Cameron said: “Britain will be able to have a zero rate for sanitary products, meaning the end of the tampon tax".
This was viewed as a success for an online petition fighting to get rid of the tampon tax called 'Stop taxing periods. Period', which had obtained over 320,000 signatures.
Bu two months on the tax has not yet been scrapped, and campaigners have expressed concern that despite the Government's promise the legislation will be dropped.
Laura Coryton, 22, who launched the petition in May 2014, said Mr Osborne has “gone quiet on the matter”.
She told The Independent: “The relevant legislation has been accepted by the House of Commons and is currently going through Parliament, but no date has been published for the legislation to be passed.
“Despite Osborne's new-found freedom from EU red tape, he still hasn't followed through with his pledge. Our government doesn't seem to be interested in making that final step to change this.
“We don't want the legislation to be dropped following a dip in public pressure. It is so important that we keep the tampon tax spotlight on Osborne so that finally we can scrap this sexist and alienating tax.”
Yesterday (Saturday 21 May), Miss Coryton, who is a graduate from Goldsmith's University and now works for the Labour party, organised a demonstration outside Parliament to put pressure on the Government over the issue.
Around 50 people - mainly women - gathered to put pressure on Mr Osborne to fulfill his pledge.
Among them were women's rights campaigners from across the globe including Jennifer Weiss-Wolf, a feminist activist from New York, and Megan Mukuria, founder of Zana Africa, a charity supporting adolescent girls in Kenya.
Miss Coryton, who is a recent graduate from Goldsmith's University in London, said the demonstration went "amazingly".
"It was fantastic to have such enthusiastic support from so many of our fearless supporters. We marched the streets to make sure this final step is taken," she said.
Protesters chanted and held up banners with messages including “Stamp on tampon tax” and “Axe tampon tax” and “Do you know how much this sign cost?”, with tampons hanging from it.
Emily Lane, 23, a trainee teacher who lives in Bristol, was among the protesters. She said: “It is just important to be represented and to have those issues that normally get swept under the carpet into the public eye.
"We can't let George Osborne think that we have stepped down yet. We are so nearly there."
Manjit K Gill, founder of Binti International – a charity fighting for menstrual dignity – was also at the demonstration. She said: "The young women today came to battle for what they believe is a human right.
"It also means that homeless women in the UK may no longer have to use socks, rags or newspaper. This is the year for incredible change to smash period shame."
Last week Labour MP Paul Sherriff, who has campaigned on the issue of tampon tax, called for a windfall if retailers and manufacturers do not pass on the full tax cut to women if and when the legislation passes.
Ms Sherriff has asked for Britain's biggest retailers to provide guarantees to pass on the tax cut, and vowed to propose amendments to the Finance Bill that would provide for a windfall tax if retailers fail to pass on the full cut.
The move follows a recent cut in VAT on women's sanitary products in France that saw firms pocketing the extra cash.